The role of FlhF and HubP as polar landmark proteins in Shewanella putrefaciens CN‐32

Abstract

SummarySpatiotemporal regulation of cell polarity plays a role in many fundamental processes in bacteria and often relies on 'landmark' proteins which recruit the corresponding clients to their designated position. Here, we explored the localization of two multi-protein complexes, the polar flagellar motor and the chemotaxis array, in Shewanella putrefaciens CN-32. We demonstrate that polar positioning of the flagellar system, but not of the chemotaxis system, depends on the GTPase FlhF. In contrast, the chemotaxis array is recruited by a transmembrane protein which we identified as the functional ortholog of Vibrio cholerae HubP. Mediated by its periplasmic N-terminal LysM domain, SpHubP exhibits an FlhF-independent localization pattern during cell cycle similar to its Vibrio counterpart and also has a role in proper chromosome segregation. In addition, while not affecting flagellar positioning, SpHubP is crucial for normal flagellar function and is involved in type IV pilimediated twitching motility. We hypothesize that a group of HubP/FimV homologs, characterized by a rather conserved N-terminal periplasmic section required for polar targeting and a highly variable acidic cytoplasmic part, primarily mediating recruitment of client proteins, serves as polar markers in various bacterial species with respect to different cellular functions.

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps

“…To visualize the flagellar filaments, maleimideligated dyes were coupled to surface-exposed cysteine residues, which were specifically introduced into the flagellins, FlaA and FlaB, of the S. putrefaciens CN-32 polar flagellum as previously described (46,47). A number of motility controls ensured that the modification did not negatively affect cell motility (SI Materials and Methods).…”

Caulobacter PopZ forms an intrinsically disordered hub in organizing bacterial cell poles

“…Bacillus subtilis DivIVA interacts directly with at least five different binding proteins, including a tethering factor that is important for partitioning the chromosomal centromere into the developing forespore (4). In Gammaproteobacteria, a hub-like transmembrane protein called HubP is targeted to cell poles via a periplasmic domain, and the cytoplasmic region of HubP recruits flagellar assembly components, chemotaxis arrays, and the chromosome centromere partitioning protein ParA (5,6).…”

The Conserved Tetratricopeptide Repeat-Containing C-Terminal Domain of Pseudomonas aeruginosa FimV Is Required for Its Cyclic AMP-Dependent and -Independent Functions

“…We downloaded all FimV ortholog sequences from the EggNOG database, which generates orthologous groups of proteins from complete genomes (33). The set of FimV ortholog sequences (COG3170) contained 235 sequences, including the previously characterized proteins FimV from Legionella pneumophila (47), TspA from Neisseria meningitidis (48), and HubP from V. cholerae and S. putrefaciens (27,28). A multiple-sequence alignment was constructed based on the full-length sequence of FimV orthologs and the resulting phylogenetic tree revealed three major clades, exemplified by FimV from P. aeruginosa, HubP, and TspA, respectively ( Fig.…”

“…Based on recent work in other species, FimV may be a hub protein, similar to HubP of Vibrio cholerae and Shewanella putrefaciens, that coordinates interactions of a number of landmark proteins involved in motility and chromosome segregation at the poles of rod-shaped bacteria (27,28). These large proteins have very limited sequence identity aside from their LysM motifs, single transmembrane segment, and a highly conserved "FimV C-terminal sequence" of ϳ50 residues (NCBI Conserved Domain Database designation TIGR03504) (18) predicted to include a single TPR motif.…”