Clusters of Charged Residues at the C Terminus of MotA and N Terminus of MotB Are Important for Function of the <i>Escherichia coli</i> Flagellar Motor

Abstract

MotA contains a conserved C-terminal cluster of negatively charged residues, and MotB contains a conserved N-terminal cluster of positively charged residues. Charge-altering mutations affecting these residues impair motility but do not diminish Mot protein levels. The motility defects are reversed by second-site mutations targeting the same or partner protein.