Professor Ben Luisi - University of Cambridge

Dynamic ribonucleoprotein complexes in the control of bacterial gene expression

In diverse bacteria, multi-enzyme assemblies, known as RNA degradosome, act in conjunction with RNA chaperones and regulatory RNA to play a key role in the post- transcriptional control of gene expression. We describe the components and organisation of representative RNA degradosomes, and we present data that support a model for a highly dynamic assembly that can act cooperatively through allosteric conformational switching and clustering. In many bacteria, the RNA-binding protein Hfq and other RNA chaperones facilitate the action of small regulatory RNAs in post- transcriptional control processes. A model will be described proposing how Hfq works in conjunction with some regulatory RNAs to guide ribonuclease machinery for action on targeted transcripts. Hfq can form higher-order regulatory assemblies directly on mRNAs, and structural polymorphism of the ribonucleoprotein assemblies enables selective translational repression of hundreds of different target mRNAs. This system suggests how highly complex regulatory pathways can evolve and be rewired with a simple economy of protein components.