Essential and non‐essential interactions in interactome networks: the Escherichia coli division proteins FtsQ–FtsN interaction

Abstract

The Escherichia coli division protein FtsQ, which plays a central role in the septosome assembly, interacts with several protein partners of the division machinery. Its interaction with FtsB and FtsL allows the formation of the trimeric complex connecting the early cytoplasmic cell division proteins with the late, essentially periplasmic, ones. Little is known about the interactions that FtsQ contracts with other divisome components, besides the fact that all are localized in its periplasmic domain. In this domain, two independent subdomains, both involved in FtsQ, FtsI and FtsN interactions, were also identified. The study of FtsQ interaction-defective mutants constituted a basis to investigate the biological significance of its interactions. However, in the case of interactions where two independent sites are involved, mutation(s) in one domain can be suppressed by the presence of the still-functional second interaction region. To ascertain the biological role of these interactions, it is therefore necessary to select double mutants, where both sites are impaired. This paper describes the behaviour of FtsQ double mutants that have lost the ability to interact with FtsN, which is the last component in the hierarchy of divisome assembly, and is necessary to guarantee its stability and function.

Splitsville: structural and functional insights into the dynamic bacterial Z ring

“…Therefore, it is likely that ZipA does not directly recruit anything, and we propose that instead it may stimulate divisome protein recruitment indirectly via promotion of a higher-order FtsZ structure such as protofilament bundling 51 . Although genetic and cytological assays implicate direct interactions between some proto-ring and later divisome proteins 87,88 , the most compelling biochemical evidence to date for interactions between early and late proteins is the direct interaction between subdomain 1c of FtsA and the cytoplasmic tail of FtsN 89 . Subdomain 1c, which is unique to FtsA and not present in other actin homologs, is required for recruitment of the late divisome proteins 90 (Figure 2B–C).…”

An Updated Model of the Divisome: Regulation of the Septal Peptidoglycan Synthesis Machinery by the Divisome

“…The protein consists of a small cytoplasmic domain, a transmembrane domain, and a large periplasmic domain containing a PG SPOR domain ( Figure 8 ). FtsN interacts with FtsA in the cytosol and with FtsQ in the periplasm, which indicates that it is partly recruited by these interactions [ 33 , 85 ]. Indeed, FtsN recruitment requires at least both FtsA and FtsQ, as was shown by the ‘premature targeting’ of different late divisome proteins [ 24 ].…”

The distinctive cell division interactome of Neisseria gonorrhoeae

“…E. coli encodes ten essential cell division proteins, including FtsZ, FtsA, ZipA, FtsK, FtsQ, FtsB, FtsL, FtsW, FtsI, and FtsN [ 11 , 12 ]. Assembly of the FtsZ-ring structure is initiated with the polymerization of FtsZ, driven by GTP hydrolysis, at the mid-cell [ 13 ].…”