Role of staphylococcal wall teichoic acid in targeting the major autolysin Atl

Abstract

SummaryStaphylococcal cell separation depends largely on the bifunctional autolysin Atl that is processed to amidase-R1,2 and R3-glucosaminidase. These murein hydrolases are targeted via repeat domains (R) to the septal region of the cell surface, thereby allowing localized peptidoglycan hydrolysis and separation of the dividing cells. Here we show that targeting of the amidase repeats is based on an exclusion strategy mediated by wall teichoic acid (WTA). In Staphylococcus aureus wild-type, externally applied repeats (R1,2) or endogenously expressed amidase were localized exclusively at the cross-wall region, while in DtagO mutant that lacks WTA binding was evenly distributed on the cell surface, which explains the increased fragility and autolysis susceptibility of the mutant. WTA prevented binding of Atl to the old cell wall but not to the cross-wall region suggesting a lower WTA content. In binding studies with ConcanavalinAfluorescein (ConA-FITC) conjugate that binds preferentially to teichoic acids, ConA-FITC was bound throughout the cell surface with the exception of the cross wall. ConA binding suggest that either content or polymerization of WTA gradually increases with distance from the cross-wall. By preventing binding of Atl, WTA directs Atl to the cross-wall to perform the last step of cell division, namely separation of the daughter cells.

Dual Targeting of Cell Wall Precursors by Teixobactin Leads to Cell Lysis

“…Localization of Atl on the cell surface exposed to antibiotics was determined similarly to a previous study (21). Antimicrobial agents at 10ϫ MIC were added to mid-exponential-phase HG003 cells in MHB, and the cells were cultivated for an additional 30 min.…”

“…The localization of Atl at the septum to mediate cell division has been proposed to occur via exclusion from the rest of the cell wall by the presence of teichoic acids (21). In the absence of WTA, Atl binding on the cell surface is delocalized, causing lysis (21). Furthermore, WTA are required for ␤-lactam resistance in methicillin-resistant S. aureus, and the cells which lack WTA are sensitized to ␤-lactam-induced cell lysis (26)(27)(28).…”

“…It has been proposed that teichoic acids control autolysin binding to peptidoglycan by an exclusion principle, whereby cell wall teichoic acid interaction with peptidoglycan inhibits autolysin binding (21,34). Consequently, an absence of teichoic acids at the septum facilitates appropriate localization of autolysins during cell division.…”

“…The localization of Atl at the septum to mediate cell division has been proposed to occur via exclusion from the rest of the cell wall by the presence of teichoic acids (21). In the absence of WTA, Atl binding on the cell surface is delocalized, causing lysis (21).…”

“…Consequently, an absence of teichoic acids at the septum facilitates appropriate localization of autolysins during cell division. It was also shown that mutation of tarO results in delocalization of amidase (21). Atl possesses three repeat sequences, each about 150 amino acids long (R 1-3 ), which bind to peptidoglycan (19,35).…”