A new route for polar navigation

Abstract

Placement of motility structures at the poles of rod-shaped bacteria is a common engineering problem with a variety of potential solutions. While investigating the mechanisms for positioning of the single polar flagellum of Pseudomonas aeruginosa, Cowles and colleagues discovered a new membrane-bound three-component system related to TonB-ExbB-ExbD that they named 'Poc' for polar organelle co-ordinator, which controls polar localization of both the flagellum and type IV pili. The Poc complex itself is not found at the poles, and is required for increased expression of pilus genes upon surface association, suggesting a new paradigm of localization control.

The Diguanylate Cyclase HsbD Intersects with the HptB Regulatory Cascade to Control Pseudomonas aeruginosa Biofilm and Motility

“…(B) Localization dynamics of HsbD (green square) during cell division. FhlF (red square) dynamics is reported as commented previously by Burrows LL [49]. Green gradient in the cell undergoing division illustrates bimodal distribution of c-di-GMP levels as reported by Christen and colleagues [14].…”

“…FlhF position during cell division has been previously described to be coordinated throughout the cell cycle [48]. Briefly, FlhF localizes at the old cell pole and when the cell engages in division it is recruited to the opposite new pole (emerging from the previous cell division), where a new flagellum will be subsequently assembled [48, 49]. Newly-formed puncta can thus be seen at the new pole during cell division, reestablishing a FlhF bipolar localization pattern in daughter cells with the brightest intensity located at the flagellated pole [48].…”

The Type IVa Pilus Machinery Is Recruited to Sites of Future Cell Division

“…The cytoplasmic member of the alignment subcomplex, PilM, has pronounced structural similarity (Cα root mean square deviation of 1.9 Å over 257 residues) to the early divisome protein, FtsA, a peripheral IM protein whose interaction with FtsZ tethers the latter to the membrane ( 18 , 19 ). On the basis of its structural mimicry of FtsA and its peripheral membrane localization via the binding to PilN’s amino terminus, we previously hypothesized ( 25 ) that PilM—and thus the alignment subcomplex—might be recruited to a midcell position through interactions with the FtsZ ring. However, mCherry-PilO exhibited polar and midcell localization in a pilM mutant ( Fig.…”

Biogenesis of Pseudomonas aeruginosa type IV pili and regulation of their function

“…The AMIN domain of AmiC, an Escherichia coli N ‐acetylmuramoyl‐L‐alanine amidase responsible for the final stages of daughter cell separation, binds PG and is proposed to target the protein to the septum where it participates in daughter cell separation (Rocaboy et al ., ). In PilQ, the AMIN domain could help to target the secretin subunits to nascent poles as cell division is occurring, to allow for incorporation of the large multimeric secretin into the cell wall as the PG is newly synthesized (Scheurwater et al ., ; Burrows, ). This domain could also play a role in anchoring the secretin and/or assembly system into the cell wall, acting with FimV and/or the TsaP homologue PA0020 to brace the assembly system against forces generated by retraction of the pilus fibre (Wehbi et al ., ; Siewering et al ., ).…”