Serine 26 in the PomB subunit of the flagellar motor is essential for hypermotility of Vibrio cholerae

• Published in: PloS one 2015-04, Vol.10 (4), p.e0123518-e0123518
• Main Authors: Halang, Petra, Vorburger, Thomas, Steuber, Julia
• Format: Article
• Language: English
• Subjects: Amino acids; Analysis; Aspartic Acid - genetics; Aspartic Acid - metabolism; Bacillus clausii; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Cholera toxin; Data processing; E coli; Electrochemistry; Escherichia coli; Flagella; Flagella - chemistry; Flagella - genetics; Flagella - metabolism; Gene Expression; Hydrogen; Hydrogen Bonding; Hydrogen bonds; Hydrogen-Ion Concentration; Ion Transport; Motility; Movement; pH effects; Protein Structure, Secondary; Protein Structure, Tertiary; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; Proteins; Salmonella; Serine; Serine - genetics; Serine - metabolism; Sodium; Sodium - metabolism; Sodium Channels - chemistry; Sodium Channels - genetics; Sodium Channels - metabolism; Swimming; Vibrio cholerae; Vibrio cholerae - chemistry; Vibrio cholerae - genetics; Vibrio cholerae - metabolism; Water - metabolism; Water-borne diseases; Waterborne diseases
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0123518

Vibrio cholerae is motile by means of its single polar flagellum which is driven by the sodium-motive force. In the motor driving rotation of the flagellar filament, a stator complex consisting of subunits PomA and PomB converts the electrochemical sodium ion gradient into torque. Charged or polar residues within the membrane part of PomB could act as ligands for Na+, or stabilize a hydrogen bond network by interacting with water within the putative channel between PomA and PomB. By analyzing a large data set of individual tracks of swimming cells, we show that S26 located within the transmembrane helix of PomB is required to promote very fast swimming of V. cholerae. Loss of hypermotility was observed with the S26T variant of PomB at pH 7.0, but fast swimming was restored by decreasing the H+ concentration of the external medium. Our study identifies S26 as a second important residue besides D23 in the PomB channel. It is proposed that S26, together with D23 located in close proximity, is important to perturb the hydration shell of Na+ before its passage through a constriction within the stator channel.