Distinct and essential morphogenic functions for wall- and lipo-teichoic acids in Bacillus subtilis

Abstract

Teichoic acids (TAs) are anionic polymers that constitute a major component of the cell wall in most Gram-positive bacteria. Despite decades of study, their function has remained unclear. TAs are covalently linked either to the cell wall peptidoglycan (wall TA (WTA)) or to the membrane (lipo-TA (LTA)). We have characterized the key enzyme of LTA synthesis in Bacillus subtilis, LTA synthase (LtaS). We show that LTA is needed for divalent cation homoeostasis and that its absence has severe effects on cell morphogenesis and cell division. Inactivation of both LTA and WTA is lethal and comparison of the individual mutants suggests that they have differentiated roles in elongation (WTA) and division (LTA). B. subtilis has four ltaS paralogues and we show how their roles are partially differentiated. Two paralogues have a redundant role in LTA synthesis during sporulation and their absence gives a novel absolute block in sporulation. The crystal structure of the extracytoplasmic part of LtaS, solved at 2.4-Å resolution, reveals a phosphorylated threonine residue, which provides clues about the catalytic mechanism and identifies the active site of the enzyme.

Teichoic acids are temporal and spatial regulators of peptidoglycan cross-linking in Staphylococcus aureus

“…Lack of LTA synthesis in rod-shaped Bacillus subtilis cells causes defects in the formation of the division septum and in cell separation (14), whereas lack of WTAs results in round cells (15). Moreover, enzymes involved in LTA synthesis localize predominantly at the division sites of bacteria (14), and enzymes involved in the synthesis of WTAs localize in helical patterns (16) similar to the previously described patterns of PGN synthesis observed during elongation of B. subtilis cells (17). The observation that mutants lacking LTAs have altered autolysis rates (5,18) or that interference with the synthesis of WTA in B. subtilis triggers the transcription of several genes involved in PGN synthesis (19), constitutes additional, indirect evidence that suggests a link between TAs and cell morphogenesis through an effect on the biosynthesis of PGNs, the correct assembly of which is required for proper cell division and morphogenesis.…”

“…More recently, TAs have been proposed to be involved in cell division and morphogenesis (13). Lack of LTA synthesis in rod-shaped Bacillus subtilis cells causes defects in the formation of the division septum and in cell separation (14), whereas lack of WTAs results in round cells (15). Moreover, enzymes involved in LTA synthesis localize predominantly at the division sites of bacteria (14), and enzymes involved in the synthesis of WTAs localize in helical patterns (16) similar to the previously described patterns of PGN synthesis observed during elongation of B. subtilis cells (17).…”

Small molecule inhibitor of lipoteichoic acid synthesis is an antibiotic for Gram-positive bacteria

“…The 3D structure of the extracellular catalytic domain of LtaS has been determined (17,20). Overall, extracellular catalytic domain of LtaS (eLtaS) assumes a sulfatase-like fold; however, its active site is distinct from that of sulfatases (20).…”

“…Characterization of LtaS in Bacillus anthracis, Bacillus subtilis, and Listeria monocytogenes confirmed that membrane proteins with pfam00884 domains are indeed responsible for the synthesis of polyglycerol-phosphate LTA (7). Where examined, ltaS mutants exhibited diminished viability, increased cell size, and altered morphology (16)(17)(18)(19). These results suggested that LtaS of Gram-positive bacteria may represent an extracellular target for the development of antibiotics against drugresistant Gram-positive bacteria.…”

Dynamics Characterization of Fully Hydrated Bacterial Cell Walls by Solid-State NMR: Evidence for Cooperative Binding of Metal Ions

“…36,37 The proposed peptidoglycan-WTA mediated binding of cations could be a key factor for storage and supply of cations essential for bacterial growth. 38 Divalent cations are known to be required for growth and survival of certain mutant strains of B. subtilis. [38][39][40] For example, a mutant lacking functional MreB, a cytoskeletal protein governing cell wall elongation, loses rodshape and viability at normal conditions but grows normally if the concentration of Mg 2+ ions is increased to 10 mM.…”