Structure-function analysis of ZapC, an FtsZ-ring stabilizer, in Escherichia coli cytokinesis
In Escherichia coli, cell division is defined by the polymerization and constriction of a cytokinetic ring (Z ring) formed by FtsZ, a tubulin-like GTPase, at midcell. Division also involves the formation of a multi-protein complex at midcell known as the divisome. Several divisome proteins promote the assembly/disassembly processes of FtsZ, thereby exercising spatiotemporal control over division. Among FtsZ regulatory proteins are the FtsZ ringassociated proteins (Zap), which either directly or indirectly stabilize the Z-ring by increasing lateral interactions amongst FtsZ protofilaments in the Z-ring. ZapA-D are recruited during early cytokinesis and have overlapping functions in stabilizing FtsZ at midcell, but share no primary sequence identity. The focus of this study is on ZapC, a small cytoplasmic protein that is conserved in the gamma proteobacteria, co-localizes with FtsZ at midcell, and promotes lateral interactions amongst FtsZ protofilaments in the Z-ring. Cells lacking ZapC show modest increase in cell lengths and overexpression of ZapC leads to aberrant hyperstable Z-rings and lethal filamentation. In this study we attempt to address the precise molecular nature of how ZapC and FtsZ interact. Genetic, molecular and structural evidence from our work suggest that residues in a basic pocket-like domain of ZapC likely interact with conserved globular domain residues of FtsZ through electrostatic interactions. A better understanding of the FtsZ-ZapC interaction at atomic details could provide clues into the biology of Z-ring assembly and stability in E. coli and related species.
Bacteria, Cytokinesis, FtsZ, Biology, Cell and Developmental Biology, Cell Biology, Immunology and Infectious Disease, Integrative Biology
City University of New York - City College
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