Autolysin-mediated peptidoglycan hydrolysis is required for the surface display of Staphylococcus aureus cell wall-anchored proteins

Abstract

Peptidoglycan hydrolases, or autolysins, play a critical role in cell wall remodeling and degradation, facilitating bacterial growth, cell division, and cell separation. In Staphylococcus aureus, the so-called “major” autolysin, Atl, has long been associated with host adhesion; however, the molecular basis underlying this phenomenon remains understudied. To investigate, we used the type V glycopeptide antibiotic complestatin, which binds to peptidoglycan and blocks the activity of autolysins, as a chemical probe of autolysin function. We also generated a chromosomally encoded, catalytically inactive variant of the Atl enzyme. Autolysin-mediated peptidoglycan hydrolysis, in particular Atl-mediated daughter cell separation, was shown to be critical for maintaining optimal surface levels of S. aureus cell wall-anchored proteins, including the fibronectin-binding proteins (FnBPs) and protein A (Spa). As such, disrupting autolysin function reduced the affinity of S. aureus for host cell ligands, and negatively impacted early stages of bacterial colonization in a systemic model of S. aureus infection. Phenotypic studies revealed that Spa was sequestered at the septum of complestatin-treated cells, highlighting that autolysins are required to liberate Spa during cell division. In summary, we reveal the hydrolytic activities of autolysins are associated with the surface display of S. aureus cell wall-anchored proteins. We demonstrate that by blocking autolysin function, type V glycopeptide antibiotics are promising antivirulence agents for the development of strategies to control S. aureus infections.

Host-induced cell wall remodelling impairs opsonophagocytosis ofStaphylococcus aureusby neutrophils

“…Cell wall thickening is due to a combination of peptidoglycan synthesis and inhibition of autolytic activity [30]. Recent work has revealed that mutants lacking the Atl autolysin have defective surface exposure of staphylococcal surface proteins, inhibiting their recognition by reactive antibodies [46]. Exposure was restored using enzymatic digestion of peptidoglycan, supporting our finding that peptidoglycan accumulation can obscure surface antigens and prevent their detection by antibodies.…”

“…Previous work indicated that WTA can block antibodies from binding to antigens within the cell wall [68]. Although WTA accumulates in the wall during host adaptation, it is currently unknown whether this contributes to concealment of IgG bound to LTA or proteins.…”

Volatile anesthetic isoflurane exposure facilitates Enterococcus biofilm infection

“…44,45 Additionally, TAs partly modulate autolysin (peptidoglycan hydrolyases) activities, 46 a cell wall hydrolytic enzyme, which is important during initial adhesion, cell lysis, and eDNA release during biofilm formation. 47,48 The downregulation of TA biosynthesis in the mutant attenuated biofilm formation, which was supported by previous research showing that the inhibition of TA biosynthesis substantially reduced E. faecalis biofilm growth. 49 Although the direct association between chloride ions and TA biosynthesis is unclear, chloride transporters are involved in various physiological processes such as maintaining ionic balance, regulating pH, and supporting cellular metabolism.…”

“…They, along with exopolysaccharides, wall‐associated proteins, and a variety of membrane constituents, form a glycocalyx, 43 in which the coalescence of adjacent glycocalyces leads to a biofilm formation 44,45 . Additionally, TAs partly modulate autolysin (peptidoglycan hydrolyases) activities, 46 a cell wall hydrolytic enzyme, which is important during initial adhesion, cell lysis, and eDNA release during biofilm formation 47,48 . The downregulation of TA biosynthesis in the mutant attenuated biofilm formation, which was supported by previous research showing that the inhibition of TA biosynthesis substantially reduced E. faecalis biofilm growth 49 …”

Rapid Screening and Comparison of Chimeric Lysins for Antibacterial Activity against Staphylococcus aureus Strains

“…Autolysins of bacteria are peptidoglycan hydrolases involved in cell wall maintenance, remodeling, growth, and separation during the life cycle and coordinate with various cell wall proteins associated with motility, adherence, nutrient transport, and virulence [ 26 , 27 , 28 , 29 ]. The catalytic domains of autolysins, such as N -acetylglucosaminidase, N -acetylmuramidase, N-acetylmuramyl-L-alanine amidase and endopeptidase, and carboxypeptidases [ 30 ], have different enzymatic functions, and the major autolysins of S. aureus are SsaA (Sle1), Atl, and LytH [ 31 , 32 , 33 ].…”