Allocation of Peptidoglycan Resources Between the Rod System and Class-A Penicillin-Binding Proteins in Myxococcus xanthus

Abstract

Peptidoglycan (PG) is a polymer scaffolding surrounding the cell membrane of bacteria and is key to survival as it aids in preserving cell structure and protects against harmful stresses. It is composed of alternating N-acetylglucosamine and N-acetylmuramic acid strands that are crosslinked through peptide chains. The synthesis of PG is a highly dynamic and tightly regulated process, spanning across the cytoplasm, inner membrane, and periplasm in gram-negative bacteria. PG synthesis is vital for cell survival and remodeling of the sacculus is required during cell elongation and division as well as during PG repair. PG synthesis has been heavily studied, however, it is still unknown how the allocation of PG precursors are portioned between the two PG synthase systems of the class-A penicillin-binding proteins and the Rod system. Here we take advantage of the monomer-dimer characteristic of the phospho-MurNAc-pentapeptide translocase protein, MraY, as a proxy for PG precursor usage of PG synthases. Using single particle tracking photoactivatable localization microscopy, we show that the Rod system is the main synthase system active in vegetative growth while aPBP���s are responsible for PG repair. This study aims to further understand the properties of PG synthesis and how the cell divides its resources during vegetative growth and repair