Displaying publications 1 - 20 of 38 in total

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  1. Anbazhagan D, Mansor M, Yan GO, Md Yusof MY, Hassan H, Sekaran SD
    PLoS One, 2012;7(7):e36696.
    PMID: 22815678 DOI: 10.1371/journal.pone.0036696
    Quorum sensing is a term that describes an environmental sensing system that allows bacteria to monitor their own population density which contributes significantly to the size and development of the biofilm. Many gram negative bacteria use N-acyl-homoserine lactones as quorum sensing signal molecules. In this study, we sought to find out if the biofilm formation among clinical isolates of Acinetobacter spp. is under the control of autoinducing quorum sensing molecules.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism*
  2. Chan KG, Puthucheary SD, Chan XY, Yin WF, Wong CS, Too WS, et al.
    Curr Microbiol, 2011 Jan;62(1):167-72.
    PMID: 20544198 DOI: 10.1007/s00284-010-9689-z
    Bacterial quorum sensing signal molecules called N-acylhomoserine lactone (AHL) controls the expression of virulence determinants in many Gram-negative bacteria. We determined AHL production in 22 Aeromonas strains isolated from various infected sites from patients (bile, blood, peritoneal fluid, pus, stool and urine). All isolates produced the two principal AHLs, N-butanoylhomoserine lactone (C4-HSL) and N-hexanoyl homoserine lactone (C6-HSL). Ten isolates also produced additional AHLs. This report is the first documentation of Aeromonas sobria producing C6-HSL and two additional AHLs with N-acyl side chain longer than C(6). Our data provides a better understanding of the mechanism(s) of this environmental bacterium emerging as a human pathogen.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism*
  3. Chan KG, Wong CS, Yin WF, Sam CK, Koh CL
    Antonie Van Leeuwenhoek, 2010 Oct;98(3):299-305.
    PMID: 20376561 DOI: 10.1007/s10482-010-9438-0
    A bacterial strain, KM1S, was isolated from a Malaysian rainforest soil sample by using a defined enrichment medium that specifically facilitates selection of quorum quenching bacteria. KM1S was clustered closely to Bacillus cereus by 16S ribosomal DNA sequence analysis. It degraded N-3-oxo-hexanoyl homoserine lactone and N-3-oxo-octanoyl homoserine lactone in vitro rapidly at 4.98 and 6.56 microg AHL h(-1) per 10(9) CFU/ml, respectively, as determined by the Rapid Resolution Liquid Chromatography. The aiiA homologue, encoding an autoinducer inactivation enzyme catalyzing the degradation of N-acylhomoserine lactones, of KM1S was amplified and cloned. Sequence analysis indicated the presence of the motif (106)HXDH-59 amino acids-H(169)-21 amino acids-D(191) for N-acylhomoserine lactone lactonases.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism*
  4. Chan KG, Liu YC, Chang CY
    Front Microbiol, 2015;6:1173.
    PMID: 26539190 DOI: 10.3389/fmicb.2015.01173
    Bacteria sense their own population size, tune the expression of responding genes, and behave accordingly to environmental stimuli by secreting signaling molecules. This phenomenon is termed as quorum sensing (QS). By exogenously manipulating the signal transduction bacterial population behaviors could be controlled, which may be done through quorum quenching (QQ). QS related regulatory networks have been proven their involvement in regulating many virulence determinants in pathogenic bacteria in the course of infections. Interfering with QS signaling system could be a novel strategy against bacterial infections and therefore requires more understanding of their fundamental mechanisms. Here we review the development of studies specifically on the inhibition of production of N-acyl-homoserine lactone (AHL), a common proteobacterial QS signal. The opportunistic pathogen, Pseudomonas aeruginosa, equips the alkylquinolone (AQ)-mediated QS which also plays crucial roles in its pathogenicity. The studies in QQ targeting on AQ are also discussed.
    Matched MeSH terms: Acyl-Butyrolactones
  5. Chan KG, Atkinson S, Mathee K, Sam CK, Chhabra SR, Cámara M, et al.
    BMC Microbiol, 2011 Mar 08;11:51.
    PMID: 21385437 DOI: 10.1186/1471-2180-11-51
    BACKGROUND: Cell-to-cell communication (quorum sensing (QS)) co-ordinates bacterial behaviour at a population level. Consequently the behaviour of a natural multi-species community is likely to depend at least in part on co-existing QS and quorum quenching (QQ) activities. Here we sought to discover novel N-acylhomoserine lactone (AHL)-dependent QS and QQ strains by investigating a bacterial community associated with the rhizosphere of ginger (Zingiber officinale) growing in the Malaysian rainforest.

    RESULTS: By using a basal growth medium containing N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) as the sole source of carbon and nitrogen, the ginger rhizosphere associated bacteria were enriched for strains with AHL-degrading capabilities. Three isolates belonging to the genera Acinetobacter (GG2), Burkholderia (GG4) and Klebsiella (Se14) were identified and selected for further study. Strains GG2 and Se14 exhibited the broadest spectrum of AHL-degrading activities via lactonolysis while GG4 reduced 3-oxo-AHLs to the corresponding 3-hydroxy compounds. In GG2 and GG4, QQ was found to co-exist with AHL-dependent QS and GG2 was shown to inactivate both self-generated and exogenously supplied AHLs. GG2, GG4 and Se14 were each able to attenuate virulence factor production in both human and plant pathogens.

    CONCLUSIONS: Collectively our data show that ginger rhizosphere bacteria which make and degrade a wide range of AHLs are likely to play a collective role in determining the QS-dependent phenotype of a polymicrobial community.

    Matched MeSH terms: Acyl-Butyrolactones/metabolism*
  6. Chang CY, Koh CL, Sam CK, Chan XY, Yin WF, Chan KG
    PLoS One, 2012;7(8):e44034.
    PMID: 22952864 DOI: 10.1371/journal.pone.0044034
    Growth-dependent cell-cell communication termed quorum sensing is a key regulatory system in bacteria for controlling gene expression including virulence factors. In this study five potential bacterial pathogens including Bacillus sp. W2.2, Klebsiella sp. W4.2, Pseudomonas sp. W3 and W3.1 and Serratia sp. W2.3 were isolated from diseased Tilapia fish in Malaysia, supplied by the leading global fish supplier. Proteolytic activity assays confirmed that with the exception of Klebsiella sp. W4.2, all isolates showed distinct proteolytic activity. Furthermore Bacillus sp. W2.2 and Pseudomonas sp. strains W3 and W3.1 also displayed haemolytic activity. By using high resolution liquid chromatography mass spectrometry, we revealed the presence of unusually long-chain N-(3-oxohexadecanoyl)-homoserine lactone (3-oxo-C16-HSL) from Pseudomonas sp. W3.1 and N-dodecanoyl-homoserine lactone (C12-HSL) from Serratia sp. W2.3, respectively. Interestingly, Pseudomonas sp. W3.1 also produced a wide range of Pseudomonas quinolone signalling (PQS) molecules. Pseudomonas sp. W3 did not show any quorum sensing properties but possessed quorum quenching activity that inactivated AHLs. This study is the first documentation that shows unusual long-chain AHLs production in Serratia sp. and Pseudomonas sp. isolated from diseased fish and the latter also produce a wide range of PQS molecules.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism*; Acyl-Butyrolactones/chemistry
  7. Chen JW, Gan HM, Yin WF, Chan KG
    J Bacteriol, 2012 Dec;194(23):6681-2.
    PMID: 23144419 DOI: 10.1128/JB.01866-12
    Roseomonas sp. strain B5 was isolated from Malaysian tropical soil that showed N-acylhomoserine lactone degradation. This is the first genome announcement of a member from the genus of Roseomonas and the first report on the quorum-quenching activity of Roseomonas spp.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism
  8. Chong TM, Tung HJ, Yin WF, Chan KG
    J Bacteriol, 2012 Dec;194(23):6611-2.
    PMID: 23144375 DOI: 10.1128/JB.01669-12
    We report the draft genome sequence of Staphylococcus sp. strain AL1, which degrades quorum-sensing molecules (namely, N-acyl homoserine lactones). To the best of our knowledge, this is the first documentation that reports the whole genome sequence and quorum-quenching activity of Staphylococcus sp. strain AL1.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism
  9. Chua KO, See-Too WS, Ee R, Lim YL, Yin WF, Chan KG
    Front Microbiol, 2019;10:1758.
    PMID: 31447806 DOI: 10.3389/fmicb.2019.01758
    The most common quorum sensing (QS) system in Gram-negative bacteria consists of signaling molecules called N-acyl-homoserine lactones (AHLs), which are synthesized by an enzyme AHL synthase (LuxI) and detected by a transcriptional regulator (LuxR) that are usually located in close proximity. However, many recent studies have also evidenced the presence of LuxR solos that are LuxR-related proteins in Proteobacteria that are devoid of a cognate LuxI AHL synthase. Pandoraea species are opportunistic pathogens frequently isolated from sputum specimens of cystic fibrosis (CF) patients. We have previously shown that P. pnomenusa strains possess QS activity. In this study, we examined the presence of QS activity in all type strains of Pandoraea species and acquired their complete genome sequences for holistic bioinformatics analyses of QS-related genes. Only four out of nine type strains (P. pnomenusa, P. sputorum, P. oxalativorans, and P. vervacti) showed QS activity, and C8-HSL was the only AHL detected. A total of 10 canonical luxIs with adjacent luxRs were predicted by bioinformatics from the complete genomes of aforementioned species and publicly available Pandoraea genomes. No orphan luxI was identified in any of the genomes. However, genes for two LuxR solos (LuxR2 and LuxR3 solos) were identified in all Pandoraea genomes (except two draft genomes with one LuxR solo gene), and P. thiooxydans was the only species that harbored no QS-related activity and genes. Except the canonical LuxR genes, LuxIs and LuxR solos of Pandoraea species were distantly related to the other well-characterized QS genes based on phylogenetic clustering. LuxR2 and LuxR3 solos might represent two novel evolutionary branches of LuxR system as they were found exclusively only in the genus. As a few luxR solos were located in close proximity with prophage sequence regions in the genomes, we thus postulated that these luxR solos could be transmitted into genus Pandoraea by transduction process mediated by bacteriophage. The bioinformatics approach developed in this study forms the basis for further characterization of closely related species. Overall, our findings improve the current understanding of QS in Pandoraea species, which is a potential pharmacological target in battling Pandoraea infections in CF patients.
    Matched MeSH terms: Acyl-Butyrolactones
  10. Ee R, Lim YL, Tee KK, Yin WF, Chan KG
    Sensors (Basel), 2014 Mar 12;14(3):5136-46.
    PMID: 24625739 DOI: 10.3390/s140305136
    Quorum sensing is a unique bacterial communication system which permits bacteria to synchronize their behaviour in accordance with the population density. The operation of this communication network involves the use of diffusible autoinducer molecules, termed N-acylhomoserine lactones (AHLs). Serratia spp. are well known for their use of quorum sensing to regulate the expression of various genes. In this study, we aimed to characterized the AHL production of a bacterium designated as strain RB-25 isolated from a former domestic waste landfill site. It was identified as Serratia fonticola using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry analysis and this was confirmed by 16S ribosomal DNA sequencing. High resolution triple quadrupole liquid chromatography-mass spectrometry analysis of S. fonticola strain RB-25 spent culture supernatant indicated the existence of three AHLs namely: N-butyryl-L-homoserine lactone (C4-HSL), N-hexanoyl-L-homoserine lactone (C6-HSL) and N-(3-oxohexanoyl) homoserine-lactone (3-oxo-C6 HSL). This is the first report of the production of these AHLs in S. fonticola.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism
  11. Gan HM, Dailey LK, Halliday N, Williams P, Hudson AO, Savka MA
    PeerJ, 2016;4:e2332.
    PMID: 27635318 DOI: 10.7717/peerj.2332
    Members of the genus Novosphingobium have been isolated from a variety of environmental niches. Although genomics analyses have suggested the presence of genes associated with quorum sensing signal production e.g., the N-acyl-homoserine lactone (AHL) synthase (luxI) homologs in various Novosphingobium species, to date, no luxI homologs have been experimentally validated.
    Matched MeSH terms: Acyl-Butyrolactones
  12. Gan HM, Chew TH, Hudson AO, Savka MA
    J Bacteriol, 2012 Sep;194(18):5137-8.
    PMID: 22933764 DOI: 10.1128/JB.01159-12
    Novosphingobium sp. strain Rr 2-17 is an N-acyl homoserine lactone (AHL)-producing bacterium isolated from the crown gall tumor of a grapevine. To our knowledge, this is the first draft genome announcement of a plant-associated strain from the genus Novosphingobium.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism
  13. Gan HY, Gan HM, Tarasco AM, Busairi NI, Barton HA, Hudson AO, et al.
    Genome Announc, 2014;2(6).
    PMID: 25377711 DOI: 10.1128/genomeA.01133-14
    Here, we report the whole-genome sequences and annotation of five oligotrophic bacteria from two sites within the Lechuguilla Cave in the Carlsbad Caverns National Park, NM. Three of the five genomes contain an acyl-homoserine lactone signal synthase ortholog (luxI) that is involved in cell-to-cell communication via quorum sensing.
    Matched MeSH terms: Acyl-Butyrolactones
  14. Ghani NA, Norizan SN, Chan XY, Yin WF, Chan KG
    Sensors (Basel), 2014;14(7):11760-9.
    PMID: 24995373 DOI: 10.3390/s140711760
    We report the degradation of quorum sensing N-acylhomoserine lactone molecules by a bacterium isolated from a Malaysian marine water sample. MALDI-TOF and phylogenetic analysis indicated this isolate BM1 clustered closely to Labrenzia sp. The quorum quenching activity of this isolate was confirmed by using a series of bioassays and rapid resolution liquid chromatography analysis. Labrenzia sp. degraded a wide range of N-acylhomoserine lactones namely N-(3-hexanoyl)-L-homoserine lactone (C6-HSL), N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) and N-(3-hydroxyhexanoyl)-L-homoserine lactone (3-hydroxy-C6-HSL). Re-lactonisation bioassays confirmed Labrenzia sp. BM1 degraded these signalling molecules efficiently via lactonase activity. To the best of our knowledge, this is the first documentation of a Labrenzia sp. capable of degrading N-acylhomoserine lactones and confirmation of its lactonase-based mechanism of action.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism*
  15. Ghani NA, Sulaiman J, Ismail Z, Chan XY, Yin WF, Chan KG
    Sensors (Basel), 2014;14(4):6463-73.
    PMID: 24721765 DOI: 10.3390/s140406463
    Two microbial isolates from a Malaysian shoreline were found to be capable of degrading N-acylhomoserine lactones. Both Matrix Assisted Laser Desorption Ionization-Time of Flight-Mass Spectrometry and 18S rDNA phylogenetic analyses confirmed that these isolates are Rhodotorula mucilaginosa. Quorum quenching activities were detected by a series of bioassays and rapid resolution liquid chromatography analysis. The isolates were able to degrade various quorum sensing molecules namely N-hexanoyl-L-homoserine lactone (C6-HSL), N-(3-oxo-hexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) and N-(3-hydroxyhexanoyl)-L-homoserine lactone (3-hydroxy-C6-HSL). Using a relactonisation assay to verify the quorum quenching mechanism, it is confirmed that Rh. mucilaginosa degrades the quorum sensing molecules via lactonase activity. To the best of our knowledge, this is the first documentation of the fact that Rh. mucilaginosa has activity against a broad range of AHLs namely C6-HSL, 3-oxo-C6-HSL and 3-hydroxy-C6-HSL.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism
  16. Goh SY, Tan WS, Khan SA, Chew HP, Abu Kasim NH, Yin WF, et al.
    Sensors (Basel), 2014;14(5):8940-9.
    PMID: 24854358 DOI: 10.3390/s140508940
    Bacteria realize the ability to communicate by production of quorum sensing (QS) molecules called autoinducers, which regulate the physiological activities in their ecological niches. The oral cavity could be a potential area for the presence of QS bacteria. In this study, we report the isolation of a QS bacterial isolate C10B from dentine caries. Preliminary screening using Chromobacterium violaceum CV026 biosensor showed that isolate C10B was able to produce N-acylhomoserine lactones (AHLs). This bacterium was further identified as a member of Burkholderia, an opportunistic pathogen. The isolated Burkholderia sp. was confirmed to produce N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL), N-decanoyl-L-homoserine lactone (C10-HSL) and N-dodecanoyl-L-homoserine lactone (C12-HSL).
    Matched MeSH terms: Acyl-Butyrolactones/analysis; Acyl-Butyrolactones/metabolism*
  17. Hong KW, Gan HM, Low SM, Lee PK, Chong YM, Yin WF, et al.
    J Bacteriol, 2012 Dec;194(23):6610.
    PMID: 23144374 DOI: 10.1128/JB.01619-12
    Pantoea sp. strain A4 is a Gram-negative bacterium isolated from the Rafflesia flower. We present here, for the first time, the genome sequence of Rafflesia-associated Pantoea sp. strain A4, which exhibited quorum-sensing activity.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism
  18. Kher HL, Krishnan T, Letchumanan V, Hong KW, How KY, Lee LH, et al.
    Gene, 2019 Feb 05;684:58-69.
    PMID: 30321658 DOI: 10.1016/j.gene.2018.10.031
    In the phylum of Proteobacteria, quorum sensing (QS) system is widely driven by synthesis and response of N-acyl homoserine lactone (AHL) signalling molecules. AHL is synthesized by LuxI homologue and sensed by LuxR homologue. Once the AHL concentration achieves a threshold level, it triggers the regulation of target genes. In this study, QS activity of Citrobacter amalonaticus strain YG6 which was isolated from clams was investigated. In order to characterise luxI/R homologues, the genome of C. amalonaticus strain YG6 (4.95 Mbp in size) was sequenced using Illumina MiSeq sequencer. Through in silico analysis, a pair of canonical luxI/R homologues and an orphan luxR homologue were identified and designated as camI, camR, and camR2, respectively. A putative lux box was identified at the upstream of camI. The camI gene was cloned and overexpressed in E. coli BL21 (DE3)pLysS. High-resolution triple quadrupole liquid chromatography mass spectrometry (LC-MS/MS) analysis verified that the CamI is a functional AHL synthase which produced multiple AHL species, namely N‑butyryl‑l‑homoserine lactone (C4-HSL), N‑hexanoyl‑l‑homoserine lactone (C6-HSL), N‑octanoyl‑l‑homoserine lactone (C8-HSL), N‑tetradecanoyl‑l‑homoserine lactone (C14-HSL) and N‑hexadecanoyl‑l‑homoserine lactone (C16-HSL) in C. amalonaticus strain YG6 and camI gene in recombinant E. coli BL21(DE3)pLysS. To our best knowledge, this is the first functional study report of camI as well as the first report describing the production of C14-HSL by C. amalonaticus.
    Matched MeSH terms: Acyl-Butyrolactones
  19. Kwasiborski A, Mondy S, Chong TM, Barbey C, Chan KG, Beury-Cirou A, et al.
    Heredity (Edinb), 2015 May;114(5):476-84.
    PMID: 25585922 DOI: 10.1038/hdy.2014.121
    Social bacteria use chemical communication to coordinate and synchronize gene expression via the quorum-sensing (QS) regulatory pathway. In Pectobacterium, a causative agent of the blackleg and soft-rot diseases on potato plants and tubers, expression of the virulence factors is collectively controlled by the QS-signals N-acylhomoserine lactones (NAHLs). Several soil bacteria, such as the actinobacterium Rhodococcus erythropolis, are able to degrade NAHLs, hence quench the chemical communication and virulence of Pectobacterium. Here, next-generation sequencing was used to investigate structural and functional genomics of the NAHL-degrading R. erythropolis strain R138. The R. erythropolis R138 genome (6.7 Mbp) contained a single circular chromosome, one linear (250 kbp) and one circular (84 kbp) plasmid. Growth of R. erythropolis and P. atrosepticum was not altered in mixed-cultures as compared with monocultures on potato tuber slices. HiSeq-transcriptomics revealed that no R. erythropolis genes were differentially expressed when R. erythropolis was cultivated in the presence vs absence of the avirulent P. atrosepticum mutant expI, which is defective for QS-signal synthesis. By contrast 50 genes (<1% of the R. erythropolis genome) were differentially expressed when R. erythropolis was cultivated in the presence vs absence of the NAHL-producing virulent P. atrosepticum. Among them, quantitative real-time reverse-transcriptase-PCR confirmed that the expression of some alkyl-sulfatase genes decreased in the presence of a virulent P. atrosepticum, as well as deprivation of organic sulfur such as methionine, which is a key precursor in the synthesis of NAHL by P. atrosepticum.
    Matched MeSH terms: Acyl-Butyrolactones/metabolism
  20. Lai WX, Gan HM, Hudson AO, Savka MA
    Genome Announc, 2016;4(1).
    PMID: 26847900 DOI: 10.1128/genomeA.01695-15
    The whole-genome sequence of a new genospecies of Methylobacterium sp., named GXS13 and isolated from grapevine xylem sap, is reported and demonstrates potential for methylotrophy, cytokinin synthesis, and cell wall modification. In addition, biosynthetic gene clusters were identified for cupriachelin, carotenoid, and acyl-homoserine lactone using the antiSMASH server.
    Matched MeSH terms: Acyl-Butyrolactones
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