AUTHOR=Pecina Anna , Schwan Meike , Blagotinsek Vitan , Rick Tim , Klüber Patrick , Leonhard Tabea , Bange Gert , Thormann Kai M. 

TITLE=The Stand-Alone PilZ-Domain Protein MotL Specifically Regulates the Activity of the Secondary Lateral Flagellar System in Shewanella putrefaciens

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.668892

DOI=10.3389/fmicb.2021.668892

ISSN=1664-302X

ABSTRACT=A number of bacterial species control the function of the flagellar motor in response to levels of the secondary messenger c-di-GMP, which is often mediated by c-di-GMP-binding proteins that act as molecular brakes or clutches to slow motor rotation. The gammaproteobacterium Shewanella putrefaciens possesses two distinct flagellar systems, the primary single polar flagellum and a secondary system with one to five lateral flagellar filaments. Here we identified a protein, MotL, which specifically regulates the activity of the lateral, but not the polar flagellar motors in response to c-di-GMP levels. MotL only consists of a single PilZ domain binding c-di-GMP, which is crucial for function. Deletion and overproduction analyses revealed that MotL slows down lateral flagella at elevated levels of c-di-GMP and may speed up lateral flagellar-mediated movement at low c-di-GMP concentrations. In vitro interaction studies hint at an interaction of MotL with the C-ring of the lateral flagellar motors. This study shows a differential c-di-GMP-dependent regulation of two flagellar systems in a single species and implicates that PilZ domain-only proteins can also act as molecular regulators to control flagella-mediated motility in bacteria.