title: Distinct pathways for modification of the bacterial cell wall by non-canonical D-amino acids.
abstract: Production of non-canonical D-amino acids (NCDAAs) in stationary phase promotes remodelling of peptidoglycan (PG), the polymer that comprises the bacterial cell wall. Impairment of NCDAAs production leads to excessive accumulation of PG and hypersensitivity to osmotic shock; however, the mechanistic bases for these phenotypes were not previously determined. Here, we show that incorporation of NCDAAs into PG is a critical means by which NCDAAs control PG abundance and strength. We identified and reconstituted in vitro two (of at least three) distinct processes that mediate NCDAA incorporation. Diverse bacterial phyla incorporate NCDAAs into their cell walls, either through periplasmic editing of the mature PG or via incorporation into PG precursor subunits in the cytosol. Production of NCDAAs in Vibrio cholerae requires the stress response sigma factor RpoS, suggesting that NCDAAs may aid bacteria in responding to varied environmental challenges. The widespread capacity of diverse bacteria, including non-producers, to incorporate NCDAAs suggests that these amino acids may serve as both autocrine- and paracrine-like regulators of chemical and physical properties of the cell wall in microbial communities.
authors.affiliation: Department of Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School and HHMI, Boston, MA, USA.
authors.forename: Felipe
authors.initials: F
authors.lastname: Cava
authors.forename: Miguel A
authors.initials: MA
authors.lastname: de Pedro
authors.forename: Hubert
authors.initials: H
authors.lastname: Lam
authors.forename: Brigid M
authors.initials: BM
authors.lastname: Davis
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Waldor
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis / Q000187:drug effects*; D010458:Peptidyl Transferases / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014734:Vibrio cholerae / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D010457:Peptidoglycan; D010458:Peptidyl Transferases; D010453:Peptide Synthases