The diguanylate cyclase AdrA regulates flagellar biosynthesis in Pseudomonas fluorescens F113 through SadB

Sci Rep. 2019 May 30;9(1):8096. doi: 10.1038/s41598-019-44554-z.

Abstract

Flagellum mediated motility is an essential trait for rhizosphere colonization by pseudomonads. Flagella synthesis is a complex and energetically expensive process that is tightly regulated. In Pseudomonas fluorescens, the regulatory cascade starts with the master regulatory protein FleQ that is in turn regulated by environmental signals through the Gac/Rsm and SadB pathways, which converge in the sigma factor AlgU. AlgU is required for the expression of amrZ, encoding a FleQ repressor. AmrZ itself has been shown to modulate c-di-GMP levels through the control of many genes encoding enzymes implicated in c-di-GMP turnover. This cyclic nucleotide regulates flagellar function and besides, the master regulator of the flagellar synthesis signaling pathway, FleQ, has been shown to bind c-di-GMP. Here we show that AdrA, a diguanylate cyclase regulated by AmrZ participates in this signaling pathway. Epistasis analysis has shown that AdrA acts upstream of SadB, linking SadB with environmental signaling. We also show that SadB binds c-di-GMP with higher affinity than FleQ and propose that c-di-GMP produced by AdrA modulates flagella synthesis through SadB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism*
  • Cyclic GMP / analogs & derivatives*
  • Cyclic GMP / metabolism
  • Escherichia coli Proteins / metabolism*
  • Flagella / metabolism*
  • Gene Expression Regulation, Bacterial
  • Organelle Biogenesis
  • Phosphorus-Oxygen Lyases / metabolism*
  • Pseudomonas fluorescens / cytology
  • Pseudomonas fluorescens / genetics
  • Pseudomonas fluorescens / metabolism*
  • Sigma Factor / metabolism
  • Signal Transduction / genetics
  • Trans-Activators / metabolism

Substances

  • Bacterial Proteins
  • Escherichia coli Proteins
  • Sigma Factor
  • Trans-Activators
  • bis(3',5')-cyclic diguanylic acid
  • Phosphorus-Oxygen Lyases
  • diguanylate cyclase
  • Cyclic GMP