Wall teichoic acids regulate peptidoglycan synthesis to maintain rod shape in Bacillus subtilis.

Rod-shaped bacteria such as Bacillus subtilis achieve their shape by using Rod complexes to synthesize anisotropic peptidoglycan and by limiting isotropic peptidoglycan synthesis by PBP1. Wall teichoic acids are also required for rod shape, but their role is unclear. Here we use single-cell microfluidics and microscopy to show that wall teichoic acids promote rod shape by preventing the formation of nanoscopic pores in the B. subtilis cell wall. Wall teichoic acid depletion led to pore formation within minutes, coinciding with a rapid increase in PBP1-mediated peptidoglycan synthesis, which became essential for growth, and transient arrest of Rod complexes before the onset of amorphous growth. A synthetically lethal cell wall hydrolase, LytE, also became essential during wall teichoic acid depletion, meaning that PBP1 and LytE cooperatively execute amorphous growth in the absence of teichoic acids. Our results show that wall teichoic acids maintain cell shape by preventing cell wall pore formation, thereby promoting Rod complex activity and preventing PBP1 activity.