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Fulltext Protein diversification through post-translational modifications, alternative splicing, and gene duplication

Goldtzvik Y, Sen N, Lam SD, Orengo C

Curr Opin Struct Biol, 2023 Aug;81:102640.
PMID: 37354790 DOI: 10.1016/j.sbi.2023.102640

Proteins provide the basis for cellular function. Having multiple versions of the same protein within a single organism provides a way of regulating its activity or developing novel functions. Post-translational modifications of proteins, by means of adding/removing chemical groups to amino acids, allow for a well-regulated and controlled way of generating functionally distinct protein species. Alternative splicing is another method with which organisms possibly generate new isoforms. Additionally, gene duplication events throughout evolution generate multiple paralogs of the same genes, resulting in multiple versions of the same protein within an organism. In this review, we discuss recent advancements in the study of these three methods of protein diversification and provide illustrative examples of how they affect protein structure and function.
AlphaFold2 reveals commonalities and novelties in protein structure space for 21 model organisms

Bordin N, Sillitoe I, Nallapareddy V, Rauer C, Lam SD, Waman VP, et al.

Commun Biol, 2023 Feb 08;6(1):160.
PMID: 36755055 DOI: 10.1038/s42003-023-04488-9

Deep-learning (DL) methods like DeepMind's AlphaFold2 (AF2) have led to substantial improvements in protein structure prediction. We analyse confident AF2 models from 21 model organisms using a new classification protocol (CATH-Assign) which exploits novel DL methods for structural comparison and classification. Of ~370,000 confident models, 92% can be assigned to 3253 superfamilies in our CATH domain superfamily classification. The remaining cluster into 2367 putative novel superfamilies. Detailed manual analysis on 618 of these, having at least one human relative, reveal extremely remote homologies and further unusual features. Only 25 novel superfamilies could be confirmed. Although most models map to existing superfamilies, AF2 domains expand CATH by 67% and increases the number of unique 'global' folds by 36% and will provide valuable insights on structure function relationships. CATH-Assign will harness the huge expansion in structural data provided by DeepMind to rationalise evolutionary changes driving functional divergence.
Fulltext SARS-CoV-2 spike protein predicted to form complexes with host receptor protein orthologues from a broad range of mammals

Lam SD, Bordin N, Waman VP, Scholes HM, Ashford P, Sen N, et al.

Sci Rep, 2020 Oct 05;10(1):16471.
PMID: 33020502 DOI: 10.1038/s41598-020-71936-5

SARS-CoV-2 has a zoonotic origin and was transmitted to humans via an undetermined intermediate host, leading to infections in humans and other mammals. To enter host cells, the viral spike protein (S-protein) binds to its receptor, ACE2, and is then processed by TMPRSS2. Whilst receptor binding contributes to the viral host range, S-protein:ACE2 complexes from other animals have not been investigated widely. To predict infection risks, we modelled S-protein:ACE2 complexes from 215 vertebrate species, calculated changes in the energy of the complex caused by mutations in each species, relative to human ACE2, and correlated these changes with COVID-19 infection data. We also analysed structural interactions to better understand the key residues contributing to affinity. We predict that mutations are more detrimental in ACE2 than TMPRSS2. Finally, we demonstrate phylogenetically that human SARS-CoV-2 strains have been isolated in animals. Our results suggest that SARS-CoV-2 can infect a broad range of mammals, but few fish, birds or reptiles. Susceptible animals could serve as reservoirs of the virus, necessitating careful ongoing animal management and surveillance.
Fulltext CATH: increased structural coverage of functional space

Sillitoe I, Bordin N, Dawson N, Waman VP, Ashford P, Scholes HM, et al.

Nucleic Acids Res, 2021 Jan 08;49(D1):D266-D273.
PMID: 33237325 DOI: 10.1093/nar/gkaa1079

CATH (https://www.cathdb.info) identifies domains in protein structures from wwPDB and classifies these into evolutionary superfamilies, thereby providing structural and functional annotations. There are two levels: CATH-B, a daily snapshot of the latest domain structures and superfamily assignments, and CATH+, with additional derived data, such as predicted sequence domains, and functionally coherent sequence subsets (Functional Families or FunFams). The latest CATH+ release, version 4.3, significantly increases coverage of structural and sequence data, with an addition of 65,351 fully-classified domains structures (+15%), providing 500 238 structural domains, and 151 million predicted sequence domains (+59%) assigned to 5481 superfamilies. The FunFam generation pipeline has been re-engineered to cope with the increased influx of data. Three times more sequences are captured in FunFams, with a concomitant increase in functional purity, information content and structural coverage. FunFam expansion increases the structural annotations provided for experimental GO terms (+59%). We also present CATH-FunVar web-pages displaying variations in protein sequences and their proximity to known or predicted functional sites. We present two case studies (1) putative cancer drivers and (2) SARS-CoV-2 proteins. Finally, we have improved links to and from CATH including SCOP, InterPro, Aquaria and 2DProt.
Six-year study on peripheral venous catheter-associated BSI rates in 262 ICUs in eight countries of South-East Asia: International Nosocomial Infection Control Consortium findings

Rosenthal VD, Bat-Erdene I, Gupta D, Rajhans P, Myatra SN, Muralidharan S, et al.

J Vasc Access, 2021 Jan;22(1):34-41.
PMID: 32406328 DOI: 10.1177/1129729820917259

BACKGROUND: Short-term peripheral venous catheter-associated bloodstream infection rates have not been systematically studied in Asian countries, and data on peripheral venous catheter-associated bloodstream infections incidence by number of short-term peripheral venous catheter days are not available.
METHODS: Prospective, surveillance study on peripheral venous catheter-associated bloodstream infections conducted from 1 September 2013 to 31 May 2019 in 262 intensive care units, members of the International Nosocomial Infection Control Consortium, from 78 hospitals in 32 cities of 8 countries in the South-East Asia Region: China, India, Malaysia, Mongolia, Nepal, Philippines, Thailand, and Vietnam. For this research, we applied definition and criteria of the CDC NHSN, methodology of the INICC, and software named INICC Surveillance Online System.
RESULTS: We followed 83,295 intensive care unit patients for 369,371 bed-days and 376,492 peripheral venous catheter-days. We identified 999 peripheral venous catheter-associated bloodstream infections, amounting to a rate of 2.65/1000 peripheral venous catheter-days. Mortality in patients with peripheral venous catheter but without peripheral venous catheter-associated bloodstream infections was 4.53% and 12.21% in patients with peripheral venous catheter-associated bloodstream infections. The mean length of stay in patients with peripheral venous catheter but without peripheral venous catheter-associated bloodstream infections was 4.40 days and 7.11 days in patients with peripheral venous catheter and peripheral venous catheter-associated bloodstream infections. The microorganism profile showed 67.1% were Gram-negative bacteria: Escherichia coli (22.9%), Klebsiella spp (10.7%), Pseudomonas aeruginosa (5.3%), Enterobacter spp. (4.5%), and others (23.7%). The predominant Gram-positive bacteria were Staphylococcus aureus (11.4%).
CONCLUSIONS: Infection prevention programs must be implemented to reduce the incidence of peripheral venous catheter-associated bloodstream infections.