Global control of bacterial translation by specific ribosome modification

Lead Research Organisation: John Innes Centre
Department Name: Contracts Office


Translational regulation plays a critical role in determining the responses of bacteria to their environment. Based on our extensive preliminary data, we propose that the widespread glutamate ligase RimK functions as an important, previously uncharacterized global regulator of bacterial mRNA translation. RimK adds glutamate residues to the C-terminus of ribosomal protein RpsF. Our results suggest that this modification affects both ribosomal stability and function, and induces a specific, directed change in the composition of the bacterial proteome.
Deletion of rimK leads to significantly reduced virulence in the destructive plant pathogen Pseudomonas syringae and compromises wheat rhizosphere colonisation by the biocontrol bacterium P. fluorescens. In both of these plant-associated Pseudomonads the rim operon also encodes RimA; a phosphodiesterase for the bacterial motility, virulence and biofilm controller cyclic-di-GMP (cdG). Deletion of P. fluorescens rimA induces similar plant interaction phenotypes to ?rimK. Furthermore RimA and RimK physically interact in vitro, consistent with an exciting new potential role for cdG in the control of bacterial mRNA translation.
This project will use a combination of protein biochemistry, molecular microbiology and emerging whole-cell analysis techniques (e.g. Ribo-seq, iTRAQ mass spectroscopy) to examine the relationship between the three Rim proteins and the Pseudomonas ribosome. The first objective of this proposal is to functionally characterize RimK, and to determine exactly how RimK ribosomal modification leads to altered mRNA translation. Next, we will focus on RimA/RimB and define their biological activity, interactions with RimK and the contribution of cdG to the control of RimK activity. Finally, we will investigate the physiological role of RimK translational regulation in two economically important model systems: plant virulence and pathogenicity in P. syringae, and wheat rhizosphere colonisation by P. fluorescens.


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