Displaying publications 1 - 20 of 199 in total

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  1. Gan HM, Gan HY, Ahmad NH, Aziz NA, Hudson AO, Savka MA
    PMID: 25621282 DOI: 10.3389/fcimb.2014.00188
    Here we report the draft genomes and annotation of four N-acyl homoserine lactone (AHL)-producing members from the family Sphingomonadaceae. Comparative genomic analyses of 62 Sphingomonadaceae genomes were performed to gain insights into the distribution of the canonical luxI/R-type quorum sensing (QS) network within this family. Forty genomes contained at least one luxR homolog while the genome of Sphingobium yanoikuyae B1 contained seven Open Reading Frames (ORFs) that have significant homology to that of luxR. Thirty-three genomes contained at least one luxI homolog while the genomes of Sphingobium sp. SYK6, Sphingobium japonicum, and Sphingobium lactosutens contained four luxI. Using phylogenetic analysis, the sphingomonad LuxR homologs formed five distinct clades with two minor clades located near the plant associated bacteria (PAB) LuxR solo clade. This work for the first time shows that 13 Sphingobium and one Sphingomonas genome(s) contain three convergently oriented genes composed of two tandem luxR genes proximal to one luxI (luxR-luxR-luxI). Interestingly, luxI solos were identified in two Sphingobium species and may represent species that contribute to AHL-based QS system by contributing AHL molecules but are unable to perceive AHLs as signals. This work provides the most comprehensive description of the luxI/R circuitry and genome-based taxonomical description of the available sphingomonad genomes to date indicating that the presence of luxR solos and luxI solos are not an uncommon feature in members of the Sphingomonadaceae family.
    Matched MeSH terms: Bacterial Proteins/metabolism
  2. Zainudin NA, Condon B, De Bruyne L, Van Poucke C, Bi Q, Li W, et al.
    Mol Plant Microbe Interact, 2015 Oct;28(10):1130-41.
    PMID: 26168137 DOI: 10.1094/MPMI-03-15-0068-R
    The Sfp-type 4'-phosphopantetheinyl transferase Ppt1 is required for activation of nonribosomal peptide synthetases, including α-aminoadipate reductase (AAR) for lysine biosynthesis and polyketide synthases, enzymes that biosynthesize peptide and polyketide secondary metabolites, respectively. Deletion of the PPT1 gene, from the maize pathogen Cochliobolus heterostrophus and the rice pathogen Cochliobolus miyabeanus, yielded strains that were significantly reduced in virulence to their hosts. In addition, ppt1 mutants of C. heterostrophus race T and Cochliobolus victoriae were unable to biosynthesize the host-selective toxins (HST) T-toxin and victorin, respectively, as judged by bioassays. Interestingly, ppt1 mutants of C. miyabeanus were shown to produce tenfold higher levels of the sesterterpene-type non-HST ophiobolin A, as compared with the wild-type strain. The ppt1 strains of all species were also reduced in tolerance to oxidative stress and iron depletion; both phenotypes are associated with inability to produce extracellular siderophores biosynthesized by the nonribosomal peptide synthetase Nps6. Colony surfaces were hydrophilic, a trait previously associated with absence of C. heterostrophus Nps4. Mutants were decreased in asexual sporulation and C. heterostrophus strains were female-sterile in sexual crosses; the latter phenotype was observed previously with mutants lacking Nps2, which produces an intracellular siderophore. As expected, mutants were albino, since they cannot produce the polyketide melanin and were auxotrophic for lysine because they lack an AAR.
    Matched MeSH terms: Bacterial Proteins/metabolism
  3. Alfizah H, Ramelah M
    Malays J Pathol, 2012 Jun;34(1):29-34.
    PMID: 22870595 MyJurnal
    Infection with Helicobacter pylori cagA-positive strains is associated with gastroduodenal diseases. The CagA protein is injected into gastric epithelial cells and supposedly induces morphological changes termed the 'hummingbird phenotype', which is associated with scattering and increased cell motility. The molecular mechanisms leading to the CagA-dependent morphological changes are only partially known. The present study was carried out to investigate the effect of CagA variants on the magnitude of gastric epithelial cell morphological changes. Recombinant 3' terminal domains of cagA were cloned and expressed in a gastric epithelial cell line and the hummingbird phenotype was quantified by microscopy. The 3' region of the cagA gene of Malaysian H. pylori isolates showed six sub-genotypes that differed in the structural organization of the EPIYA repeat sequences. The percentage of hummingbird cells induced by CagA increased with duration of transfection. The hummingbird phenotype was observed to be more pronounced when CagA with 4 EPIYA motifs rather than 3 or 2 EPIYA motifs was produced. The activity of different CagA variants in the induction of the hummingbird phenotype in gastric epithelial cells depends at least in part on EPIYA motif variability. The difference in CagA genotypes might influence the potential of individual CagAs to cause morphological changes in host cells. Depending on the relative exposure of cells to CagA genotypes, this may contribute to the various disease outcomes caused by H. pylori infection in different individuals.
    Matched MeSH terms: Bacterial Proteins/metabolism
  4. Zamakhaev M, Grigorov A, Bespyatykh J, Azhikina T, Goncharenko A, Shumkov M
    Arch Microbiol, 2022 Dec 15;205(1):28.
    PMID: 36520276 DOI: 10.1007/s00203-022-03363-1
    Mycobacterium tuberculosis is an extremely successful pathogen known for its ability to cause latent infection. The latter is connected with the bacterium resting state development and is considered to be based on the activity of toxin-antitoxin (TA) systems at least in part. Here we studied the physiological and proteomic consequences of VapC toxin overexpression together with the features of the protein synthesis apparatus and compared them with the characteristics of dormant mycobacterial cells in an M. smegmatis model. The findings allow suggesting the mechanism mycobacteria enter dormancy, which is realized through VapC-caused cleavage of the 23S rRNA Sarcin-Ricin loop followed by conservation of stalled ribosomes in a membrane-associated manner. The found features of resting mycobacteria protein synthesis apparatus hypothesize the mechanisms of resuscitation from dormancy through the ribosomes de-association off the membrane accompanied by the 23S rRNA break curing, and could be of value for the development of principally new antituberculosis agents.
    Matched MeSH terms: Bacterial Proteins/metabolism
  5. Yam H, Abdul Rahim A, Gim Luan O, Samian R, Abdul Manaf U, Mohamad S, et al.
    Protein J, 2012 Mar;31(3):246-9.
    PMID: 22354666 DOI: 10.1007/s10930-012-9398-5
    In this post genomic era, there are a great number of in silico annotated hypothetical genes. However, experimental validation of the functionality of these genes remains tentative. Two of the major challenges faced by researcher are whether these hypothetical genes are protein-coding genes and whether their corresponding predicted translational start codons are correct. In this report, we demonstrate a convenient procedure to validate the presence of a hypothetical gene product of BPSS1356 from Burkholderia pseudomallei as well as its start codon. It was done by integration of a His-Tag coding sequence into C-terminal end of BPSS1356 gene via homologous recombination. We then purified the native protein using affinity chromatography. The genuine start codon of BPSS1356 was then determined by protein N-terminal sequencing.
    Matched MeSH terms: Bacterial Proteins/metabolism*
  6. Kamarudin NH, Rahman RN, Ali MS, Leow TC, Basri M, Salleh AB
    Mol Biotechnol, 2014 Aug;56(8):747-57.
    PMID: 24771007 DOI: 10.1007/s12033-014-9753-1
    Terminal moieties of most proteins are long known to be disordered and flexible. To unravel the functional role of these regions on the structural stability and biochemical properties of AT2 lipase, four C-terminal end residues, (Ile-Thr-Arg-Lys) which formed a flexible, short tail-like random-coil segment were targeted for mutation. Swapping of the tail-like region had resulted in an improved crystallizability and anti-aggregation property along with a slight shift of the thermostability profile. The lipolytic activity of mutant (M386) retained by 43 % compared to its wild-type with 18 % of the remaining activity at 45 °C. In silico analysis conducted at 25 and 45 °C was found to be in accordance to the experimental findings in which the RMSD values of M386 were more stable throughout the total trajectory in comparison to its wild-type. Terminal moieties were also observed to exhibit large movement and flexibility as denoted by high RMSF values at both dynamics. Variation in organic solvent stability property was detected in M386 where the lipolytic activity was stimulated in the presence of 25 % (v/v) of DMSO, isopropanol, and diethyl ether. This may be worth due to changes in the surface charge residues at the mutation point which probably involve in protein-solvent interaction.
    Matched MeSH terms: Bacterial Proteins/metabolism*
  7. Chan WT, Garcillán-Barcia MP, Yeo CC, Espinosa M
    FEMS Microbiol Rev, 2023 Sep 05;47(5).
    PMID: 37715317 DOI: 10.1093/femsre/fuad052
    Toxin-antitoxin (TA) systems are entities found in the prokaryotic genomes, with eight reported types. Type II, the best characterized, is comprised of two genes organized as an operon. Whereas toxins impair growth, the cognate antitoxin neutralizes its activity. TAs appeared to be involved in plasmid maintenance, persistence, virulence, and defence against bacteriophages. Most Type II toxins target the bacterial translational machinery. They seem to be antecessors of Higher Eukaryotes and Prokaryotes Nucleotide-binding (HEPN) RNases, minimal nucleotidyltransferase domains, or CRISPR-Cas systems. A total of four TAs encoded by Streptococcus pneumoniae, RelBE, YefMYoeB, Phd-Doc, and HicAB, belong to HEPN-RNases. The fifth is represented by PezAT/Epsilon-Zeta. PezT/Zeta toxins phosphorylate the peptidoglycan precursors, thereby blocking cell wall synthesis. We explore the body of knowledge (facts) and hypotheses procured for Type II TAs and analyse the data accumulated on the PezAT family. Bioinformatics analyses showed that homologues of PezT/Zeta toxin are abundantly distributed among 14 bacterial phyla mostly in Proteobacteria (48%), Firmicutes (27%), and Actinobacteria (18%), showing the widespread distribution of this TA. The pezAT locus was found to be mainly chromosomally encoded whereas its homologue, the tripartite omega-epsilon-zeta locus, was found mostly on plasmids. We found several orphan pezT/zeta toxins, unaccompanied by a cognate antitoxin.
    Matched MeSH terms: Bacterial Proteins/metabolism
  8. V K, Neela VK
    Virulence, 2020 Dec;11(1):104-112.
    PMID: 31957553 DOI: 10.1080/21505594.2020.1713649
    This study investigates the twitching ability of 28 clinical and five environmental strains of S. maltophilia grown under iron-depleted condition through in-silico, phenotypic and proteomics approaches. Rapid Annotations using Subsystem Technology (RAST) analysis revealed the presence of 21 targets of type IV pilus shared across S. maltophilia strains K279a, R551-3, D457 and JV3. The macroscopic twitching assay showed that only clinical isolates produced a zone of twitching with a mean of 22.00 mm under normal and 25.00 mm under iron-depleted conditions. (p = 0.002). Environmental isolates did not show any significant twitching activity in both conditions tested. Isobaric Tags for Relative and Absolute Quantification (ITRAQ) analysis showed altered expression of twitching motility protein PilT (99.08-fold change), flagellar biosynthesis protein FliC (20.14-fold change), and fimbrial protein (0.70-fold change) in response to iron-depleted condition. Most of the strains that have the ability to twitch under the normal condition, exhibit enhanced twitching during iron limitation.
    Matched MeSH terms: Bacterial Proteins/metabolism
  9. Sarmiento ME, Alvarez N, Chin KL, Bigi F, Tirado Y, García MA, et al.
    Tuberculosis (Edinb), 2019 03;115:26-41.
    PMID: 30948174 DOI: 10.1016/j.tube.2019.01.003
    Even after decades searching for a new and more effective vaccine against tuberculosis, the scientific community is still pursuing this goal due to the complexity of its causative agent, Mycobacterium tuberculosis (Mtb). Mtb is a microorganism with a robust variety of survival mechanisms that allow it to remain in the host for years. The structure and nature of the Mtb envelope play a leading role in its resistance and survival. Mtb has a perfect machinery that allows it to modulate the immune response in its favor and to adapt to the host's environmental conditions in order to remain alive until the moment to reactivate its normal growing state. Mtb cell envelope protein, carbohydrate and lipid components have been the subject of interest for developing new vaccines because most of them are responsible for the pathogenicity and virulence of the bacteria. Many indirect evidences, mainly derived from the use of monoclonal antibodies, support the potential protective role of Mtb envelope components. Subunit and DNA vaccines, lipid extracts, liposomes and membrane vesicle formulations are some examples of technologies used, with encouraging results, to evaluate the potential of these antigens in the protective response against Mtb.
    Matched MeSH terms: Bacterial Proteins/metabolism
  10. Saallah S, Naim MN, Mokhtar MN, Abu Bakar NF, Gen M, Lenggoro IW
    Enzyme Microb Technol, 2014 Oct;64-65:52-9.
    PMID: 25152417 DOI: 10.1016/j.enzmictec.2014.06.002
    In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nanometer-order CGTase particles from aqueous suspension was demonstrated. CGTase enzyme was prepared in acetate buffer solution (1% v/v), followed by electrospraying in stable Taylor cone-jet mode. The deposits were collected on aluminium foil (collector) at variable distances from the tip of spraying needle, ranging from 10 to 25 cm. The Coulomb fission that occurs during electrospraying process successfully transformed the enzyme to the solid state without any functional group deterioration. The functional group verification was conducted by FTIR analysis. Comparison between the deposit and the as-received enzyme in dry state indicates almost identical spectra. By increasing the distance of the collector from the needle tip, the average particle size of the solidified enzyme was reduced from 200±117 nm to 75±34 nm. The average particle sizes produced from the droplet fission were in agreement with the scaling law models. Enzyme activity analysis showed that the enzyme retained its initial activity after the electrospraying process. The enzyme particles collected at the longest distance (25 cm) demonstrated the highest enzyme activity, which indicates that the activity was controlled by the enzyme particle size.
    Matched MeSH terms: Bacterial Proteins/metabolism
  11. Ghafourian S, Raftari M, Sadeghifard N, Sekawi Z
    Curr Issues Mol Biol, 2014;16:9-14.
    PMID: 23652423
    The toxin-antitoxin (TA) systems are systems in which an unstable antitoxin inhibits a stable toxin. This review aims to introduce the TA system and its biological application in bacteria. For this purpose, first we introduce a new classification for the TA systems based on how the antitoxin can neutralize the toxin, we then describe the functions of TA systems and finally review the application of these systems in biotechnology.
    Matched MeSH terms: Bacterial Proteins/metabolism
  12. Yam H, Rahim AA, Mohamad S, Mahadi NM, Manaf UA, Shu-Chien AC, et al.
    PLoS One, 2014;9(6):e99218.
    PMID: 24927285 DOI: 10.1371/journal.pone.0099218
    Burkholderia pseudomallei is an opportunistic pathogen and the causative agent of melioidosis. It is able to adapt to harsh environments and can live intracellularly in its infected hosts. In this study, identification of transcriptional factors that associate with the β' subunit (RpoC) of RNA polymerase was performed. The N-terminal region of this subunit is known to trigger promoter melting when associated with a sigma factor. A pull-down assay using histidine-tagged B. pseudomallei RpoC N-terminal region as bait showed that a hypothetical protein BPSS1356 was one of the proteins bound. This hypothetical protein is conserved in all B. pseudomallei strains and present only in the Burkholderia genus. A BPSS1356 deletion mutant was generated to investigate its biological function. The mutant strain exhibited reduced biofilm formation and a lower cell density during the stationary phase of growth in LB medium. Electron microscopic analysis revealed that the ΔBPSS1356 mutant cells had a shrunken cytoplasm indicative of cell plasmolysis and a rougher surface when compared to the wild type. An RNA microarray result showed that a total of 63 genes were transcriptionally affected by the BPSS1356 deletion with fold change values of higher than 4. The expression of a group of genes encoding membrane located transporters was concurrently down-regulated in ΔBPSS1356 mutant. Amongst the affected genes, the putative ion transportation genes were the most severely suppressed. Deprivation of BPSS1356 also down-regulated the transcriptions of genes for the arginine deiminase system, glycerol metabolism, type III secretion system cluster 2, cytochrome bd oxidase and arsenic resistance. It is therefore obvious that BPSS1356 plays a multiple regulatory roles on many genes.
    Matched MeSH terms: Bacterial Proteins/metabolism*
  13. Zainal Abidin MH, Abd Halim KB, Huyop F, Tengku Abdul Hamid TH, Abdul Wahab R, Abdul Hamid AA
    J Mol Graph Model, 2019 07;90:219-225.
    PMID: 31103914 DOI: 10.1016/j.jmgm.2019.05.003
    Dehalogenase E (DehE) is a non-stereospecific enzyme produced by the soil bacterium, Rhizobium sp. RC1. Till now, the catalytic mechanism of DehE remains unclear although several literature concerning its structure and function are available. Since DehE is non-stereospecific, the enzyme was hypothesized to follow a 'direct attack mechanism' for the catalytic breakdown of a haloacid. For a molecular insight, the DehE modelled structure was docked in silico with the substrate 2-chloropropionic acid (2CP) in the active site. The ideal position of DehE residues that allowed a direct attack mechanism was then assessed via molecular dynamics (MD) simulation. It was revealed that the essential catalytic water was hydrogen bonded to the 'water-bearer', Asn114, at a relatively constant distance of ∼2.0 Å after 50 ns. The same water molecule was also closely sited to the catalytic Asp189 at an average distance of ∼2.0 Å, signifying the imperative role of the latter to initiate proton abstraction for water activation. This reaction was crucial to promote a direct attack on the α-carbon of 2CP to eject the halide ion. The water molecule was oriented favourably towards the α-carbon of 2CP at an angle of ∼75°, mirrored by the formation of stable enzyme-substrate orientations throughout the simulation. The data therefore substantiated that the degradation of a haloacid by DehE followed a 'direct attack mechanism'. Hence, this study offers valuable information into future advancements in the engineering of haloacid dehalogenases with improved activity and selectivity, as well as functionality in solvents other than water.
    Matched MeSH terms: Bacterial Proteins/metabolism*
  14. Chung PY
    FEMS Microbiol Lett, 2016 10;363(20).
    PMID: 27664057
    Klebsiella pneumoniae is an opportunistic pathogen that commonly causes nosocomial infections in the urinary tract, respiratory tract, lung, wound sites and blood in individuals with debilitating diseases. Klebsiella pneumoniae is still a cause of severe pneumonia in alcoholics in Africa and Asia, and the predominant primary pathogen of primary liver abscess in Taiwan and Southeast Asia, particularly in Asian and Hispanic patients, and individuals with diabetes mellitus. In the United States and Europe, K. pneumoniae infections are most frequently associated with nosocomial infections. The emergence of antibiotic-resistant strains of K. pneumoniae worldwide has become a cause of concern where extended-spectrum β-lactamases (ESBLs) and carbapenemase-producing strains have been isolated with increasing frequency. The pathogen's ability to form biofilms on inserted devices such as urinary catheter has been proposed as one of the important mechanisms in nosocomially acquired and persistent infections, adding to the increased resistance to currently used antibiotics. In this review, infections caused by K. pneumoniae, antibiotic resistance and formation of biofilm will be discussed.
    Matched MeSH terms: Bacterial Proteins/metabolism
  15. Lee WC, Anton BP, Wang S, Baybayan P, Singh S, Ashby M, et al.
    BMC Genomics, 2015;16:424.
    PMID: 26031894 DOI: 10.1186/s12864-015-1585-2
    The genome of the human gastric pathogen Helicobacter pylori encodes a large number of DNA methyltransferases (MTases), some of which are shared among many strains, and others of which are unique to a given strain. The MTases have potential roles in the survival of the bacterium. In this study, we sequenced a Malaysian H. pylori clinical strain, designated UM032, by using a combination of PacBio Single Molecule, Real-Time (SMRT) and Illumina MiSeq next generation sequencing platforms, and used the SMRT data to characterize the set of methylated bases (the methylome).
    Matched MeSH terms: Bacterial Proteins/metabolism
  16. Abdul Manas NH, Pachelles S, Mahadi NM, Illias RM
    PLoS One, 2014;9(9):e106481.
    PMID: 25221964 DOI: 10.1371/journal.pone.0106481
    A maltogenic amylase (MAG1) from alkaliphilic Bacillus lehensis G1 was cloned, expressed in Escherichia coli, purified and characterised for its hydrolysis and transglycosylation properties. The enzyme exhibited high stability at pH values from 7.0 to 10.0. The hydrolysis of β-cyclodextrin (β-CD) produced malto-oligosaccharides of various lengths. In addition to hydrolysis, MAG1 also demonstrated transglycosylation activity for the synthesis of longer malto-oligosaccharides. The thermodynamic equilibrium of the multiple reactions was shifted towards synthesis when the reaction conditions were optimised and the water activity was suppressed, which resulted in a yield of 38% transglycosylation products consisting of malto-oligosaccharides of various lengths. Thin layer chromatography and high-performance liquid chromatography analyses revealed the presence of malto-oligosaccharides with a higher degree of polymerisation than maltoheptaose, which has never been reported for other maltogenic amylases. The addition of organic solvents into the reaction further suppressed the water activity. The increase in the transglycosylation-to-hydrolysis ratio from 1.29 to 2.15 and the increased specificity toward maltopentaose production demonstrated the enhanced synthetic property of the enzyme. The high transglycosylation activity of maltogenic amylase offers a great advantage for synthesising malto-oligosaccharides and rare carbohydrates.
    Matched MeSH terms: Bacterial Proteins/metabolism
  17. Schmidt HM, Andres S, Nilsson C, Kovach Z, Kaakoush NO, Engstrand L, et al.
    Eur J Clin Microbiol Infect Dis, 2010 Apr;29(4):439-51.
    PMID: 20157752 DOI: 10.1007/s10096-010-0881-7
    Helicobacter pylori-related disease is at least partially attributable to the genotype of the infecting strain, particularly the presence of specific virulence factors. We investigated the prevalence of a novel combination of H. pylori virulence factors, including the cag pathogenicity island (PAI), and their association with severe disease in isolates from the three major ethnicities in Malaysia and Singapore, and evaluated whether the cag PAI was intact and functional in vitro. Polymerase chain reaction (PCR) was used to detect dupA, cagA, cagE, cagT, cagL and babA, and to type vacA, the EPIYA motifs, HP0521 alleles and oipA ON status in 159 H. pylori clinical isolates. Twenty-two strains were investigated for IL-8 induction and CagA translocation in vitro. The prevalence of cagA, cagE, cagL, cagT, babA, oipA ON and vacA s1 and i1 was >85%, irrespective of the disease state or ethnicity. The prevalence of dupA and the predominant HP0521 allele and EPIYA motif varied significantly with ethnicity (p < 0.05). A high prevalence of an intact cag PAI was found in all ethnic groups; however, no association was observed between any virulence factor and disease state. The novel association between the HP0521 alleles, EPIYA motifs and host ethnicity indicates that further studies to determine the function of this gene are important.
    Matched MeSH terms: Bacterial Proteins/metabolism
  18. Valizadeh N, Valian F, Sadeghifard N, Karami S, Pakzad I, Kazemian H, et al.
    Drug Res (Stuttg), 2017 Jul;67(7):385-387.
    PMID: 28320039 DOI: 10.1055/s-0043-102060
    Toxin antitoxin system is a regulatory system that antitoxin inhibits the toxin. We aimed to determine the role of TA loci in biofilm formation in K. pneumoniae clinical and environmental isolates; also inhibition of biofilm formation by Peganum harmala. So, 40 K. pneumoniae clinical and environmental isolates were subjected for PCR to determine the frequency of mazEF, relEB, and mqsRA TA loci. Biofilm formation assay subjected for all isolates. Then, P. harmala was tested against positive biofilm formation strains. Our results demonstrated that relBE TA loci were dominant TA loci; whereas mqsRA TA loci were negative in all isolates. The most environmental isolates showed weak and no biofilm formation while strong and moderate biofilm formation observed in clinical isolates. Biofilm formations by K. pneumoniae in 9 ug/ml concentration were inhibited by P. harmala. In vivo study suggested to be performed to introduce Peganum harmala as anti-biofilm formation in K. pneumoniae.
    Matched MeSH terms: Bacterial Proteins/metabolism
  19. Quintero-Yanes A, Lee CM, Monson R, Salmond G
    Environ Microbiol, 2020 07;22(7):2921-2938.
    PMID: 32352190 DOI: 10.1111/1462-2920.15048
    Serratia sp. ATCC 39006 produces intracellular gas vesicles to enable upward flotation in water columns. It also uses flagellar rotation to swim through liquid and swarm across semi-solid surfaces. Flotation and motility can be co-regulated with production of a β-lactam antibiotic (carbapenem carboxylate) and a linear tripyrrole red antibiotic, prodigiosin. Production of gas vesicles, carbapenem and prodigiosin antibiotics, and motility are controlled by master transcriptional and post-transcriptional regulators, including the SmaI/SmaR-based quorum sensing system and the mRNA binding protein, RsmA. Recently, the ribose operon repressor, RbsR, was also defined as a pleiotropic regulator of flotation and virulence factor elaboration in this strain. Here, we report the discovery of a new global regulator (FloR; a DeoR family transcription factor) that modulates flotation through control of gas vesicle morphogenesis. The floR mutation is highly pleiotropic, down-regulating production of gas vesicles, carbapenem and prodigiosin antibiotics, and infection in Caenorhabditis elegans, but up-regulating flagellar motility. Detailed proteomic analysis using TMT peptide labelling and LC-MS/MS revealed that FloR is a physiological master regulator that operates through subordinate pleiotropic regulators including Rap, RpoS, RsmA, PigU, PstS and PigT.
    Matched MeSH terms: Bacterial Proteins/metabolism*
  20. Sani HA, Shariff FM, Rahman RNZRA, Leow TC, Salleh AB
    Mol Biotechnol, 2018 Jan;60(1):1-11.
    PMID: 29058211 DOI: 10.1007/s12033-017-0038-3
    The substitutions of the amino acid at the predetermined critical point at the C-terminal of L2 lipase may increase its thermostability and enzymatic activity, or even otherwise speed up the unfolding of the protein structure. The C-terminal of most proteins is often flexible and disordered. However, some protein functions are directly related to flexibility and play significant role in enzyme reaction. The critical point for mutation of L2 lipase structure was predicted at the position 385 of the L2 sequence, and the best three mutants were determined based on I-Mutant2.0 software. The best three mutants were S385E, S385I and S385V. The effects of the substitution of the amino acids at the critical point were analysed with molecular dynamics simulation by using Yet Another Scientific Artificial Reality Application software. The predicted mutant L2 lipases were found to have lower root mean square deviation value as compared to L2 lipase. It was indicated that all the three mutants had higher compactness in the structure, consequently enhanced the stability. Root mean square fluctuation analysis showed that the flexibility of L2 lipase was reduced by mutations. Purified S385E lipase had an optimum temperature of 80 °C in Tris-HCl pH 8. The highest enzymatic activity of purified S385E lipase was obtained at 80 °C temperature in Tris-HCl pH 8, while for L2 lipase it was at 70 °C in Glycine-NaOH pH 9. The thermal stability of S385V lipase was enhanced as compared to other protein since that the melting point (T m) value was at 85.96 °C. S385I lipase was more thermostable compared to recombinant L2 lipase and other mutants at temperature 60 °C within 16 h preincubation.
    Matched MeSH terms: Bacterial Proteins/metabolism*
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