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PLoS Pathog. 2015 May 7;11(5):e1004891. doi: 10.1371/journal.ppat.1004891. eCollection 2015 May.

Staphylococcus aureus Survives with a Minimal Peptidoglycan Synthesis Machine but Sacrifices Virulence and Antibiotic Resistance.

Author information

1
Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
2
Laboratory of Bacterial Cell Surface and Pathogenesis, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal; Laboratory of Genes and Development, Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
3
Instituto Gulbenkian de Ciência, Oeiras, Portugal.
4
W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America; The University of Sheffield, Department of Molecular Biology and Biotechnology, Western Bank, Sheffield, United Kingdom.
5
Merck Research Laboratories IT, Boston, Massachusetts, United States of America.
6
Infectious Disease Research, Merck Research Laboratories, Kenilworth, New Jersey, United States of America.
7
Laboratory of Bacterial Cell Surface and Pathogenesis, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
8
Laboratory of Genes and Development, Department of Biochemistry, University of Oxford, Oxford, United Kingdom.

Abstract

Many important cellular processes are performed by molecular machines, composed of multiple proteins that physically interact to execute biological functions. An example is the bacterial peptidoglycan (PG) synthesis machine, responsible for the synthesis of the main component of the cell wall and the target of many contemporary antibiotics. One approach for the identification of essential components of a cellular machine involves the determination of its minimal protein composition. Staphylococcus aureus is a Gram-positive pathogen, renowned for its resistance to many commonly used antibiotics and prevalence in hospitals. Its genome encodes a low number of proteins with PG synthesis activity (9 proteins), when compared to other model organisms, and is therefore a good model for the study of a minimal PG synthesis machine. We deleted seven of the nine genes encoding PG synthesis enzymes from the S. aureus genome without affecting normal growth or cell morphology, generating a strain capable of PG biosynthesis catalyzed only by two penicillin-binding proteins, PBP1 and the bi-functional PBP2. However, multiple PBPs are important in clinically relevant environments, as bacteria with a minimal PG synthesis machinery became highly susceptible to cell wall-targeting antibiotics, host lytic enzymes and displayed impaired virulence in a Drosophila infection model which is dependent on the presence of specific peptidoglycan receptor proteins, namely PGRP-SA. The fact that S. aureus can grow and divide with only two active PG synthesizing enzymes shows that most of these enzymes are redundant in vitro and identifies the minimal PG synthesis machinery of S. aureus. However a complex molecular machine is important in environments other than in vitro growth as the expendable PG synthesis enzymes play an important role in the pathogenicity and antibiotic resistance of S. aureus.

PMID:
25951442
PMCID:
PMC4423922
DOI:
10.1371/journal.ppat.1004891
[Indexed for MEDLINE]
Free PMC Article

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