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Phosphorylation of Bacillus subtilis gene regulator AbrB modulates its DNA-binding properties.

Research paper by Ahasanul A Kobir, Sandrine S Poncet, Vladimir V Bidnenko, Olivier O Delumeau, Carsten C Jers, Samira S Zouhir, Rosa R Grenha, Sylvie S Nessler, Phillipe P Noirot, Ivan I Mijakovic

Indexed on: 16 Apr '14Published on: 16 Apr '14Published in: Molecular Microbiology



Abstract

AbrB is a global gene regulator involved in transition phase phenomena in Bacillus subtilis. It participates in a complex regulatory network governing the expression of stationary-phase functions. AbrB was previously found to be phosphorylated on serine 86 located close to its C-terminal oligomerization domain. Here we report that AbrB can be phosphorylated by three B. subtilis serine/threonine kinases expressed during the transition and stationary phase: PrkC, PrkD and YabT. Our in vitro findings suggest that AbrB phosphorylation impedes its DNA binding and abolishes binding cooperativity. In vivo we established that a phospho-mimetic mutation abrB S86D leads to a significant loss of AbrB control over several key target functions: exoprotease production, competence development and sporulation. A wider transcriptome analysis of abrB S86D and S86A mutant strains revealed deregulation of a large number of target genes. We therefore propose that AbrB phosphorylation serves as an additional input for fine-tuning the activity of this ambiactive gene regulator.