title: Chemical probes reveal an extraseptal mode of cross-linking in Staphylococcus aureus.
abstract: Staphylococcus aureus is an important human pathogen and a model organism for studying cell wall synthesis in Gram-positive cocci. The prevailing model of cell wall biogenesis in cocci holds that peptidoglycan synthesis (i.e., transglycosylation and cross-linking) is restricted spatially to the septal cross-wall and temporally to cell division. Previously, we developed a method for visualizing cross-linking in S. aureus using fluorescently tagged mimics of the endogenous substrate of penicillin-binding proteins (PBPs). These probes are incorporated into the cell wall of S. aureus specifically by PBP4, allowing localization of the enzyme's cross-linking activity in vivo with precise spatial and temporal resolution. Here, using this methodology, we have discovered that PBP4 is active not only at the septum, but unexpectedly at the peripheral wall as well. These results challenge the long-held belief that peptidoglycan synthesis is restricted to the septum in spherical bacteria, and instead indicate the presence of two spatiotemporally distinct modes of cross-linking in S. aureus: one at the septum during cell division, and another at the peripheral wall between divisions.
authors.affiliation: §Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States.
authors.forename: Samir
authors.initials: S
authors.lastname: Gautam
authors.affiliation: §Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States.
authors.forename: Taehan
authors.initials: T
authors.lastname: Kim
authors.affiliation: §Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Spiegel
mesh_terms: D003432:Cross-Linking Reagents / Q000138:chemical synthesis / Q000737:chemistry*; D015335:Molecular Probes / Q000138:chemical synthesis / Q000737:chemistry*; D010457:Peptidoglycan / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000166:cytology*
chemical_list: D003432:Cross-Linking Reagents; D015335:Molecular Probes; D010457:Peptidoglycan