The PdeK-PdeR two-component system promotes unipolar localization of FimX and pilus extension in <i>Xanthomonas oryzae</i> pv. <i>oryzicola</i>

Abstract

and virulence in rice. PdeK and the c-di-GMP phosphodiesterase activity of PdeR were required for the unipolar localization of FimX, leading to T4P extension. High amounts of c-di-GMP reduced the affinity of FimX for PdeR in vitro, consistent with FimX promoting T4P extension only under conditions of low c-di-GMP. We propose that low intracellular amounts of c-di-GMP created by PdeR facilitate the recruitment of FimX to the leading pole of motile cells. Our findings indicate that the PdeK-PdeR two-component system connects environmental cues to second messenger turnover, resulting in a change in the intracellular concentration of c-di-GMP that promotes T4P biogenesis and virulence.