Analysis of the role of HSP100/Clp and their adaptor proteins in general and regulated proteolysis in Bacillus subtilis

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Previously we could demonstrate that the adaptor protein MecA is necessary for the regulated proteolysis of the transcription factor ComK in competence development of Bacillus subtilis by ClpCP protease. However recent experimental data demonstrate that MecA is also necessary for the recognition, disaggregation and refolding of previously heat aggregated proteins by ClpC a chaperone of the HSP 100 subfamily of AAA+ ATPases. In addition MecA enables the specific recognition and degradation of unfolded or aggregated proteins by ClpCP. A MecA paralogue YpbH shows the same activity. The adaptor proteins are therefore necessary for the general function of ClpC in protein quality control in B. subtilis. To understand the role of the adaptor proteins MecA and the paralogue YpbH in the protein quality control system of B. subtilis we want to biochemically characterise and identify the partners of the adaptor proteins. Therefore we want to test the functional interaction of MecA and YpbH with those possible partner the HSP 100 proteins ClpC, ClpE and ClpX with and without ClpP. On the other hand we want to determine the general substrate specificity of the adaptor proteins, because the connection of substrate recognition and interaction with the HSP 100 is a prerequisite for the function of this new class of proteins. In addition experiments are devised to develop an understanding of the targeting for degradation mechanism of the adaptor proteins. Finally first experiments to understand the in vivo role of these adaptor proteins and their HSP 100 partner proteins in the protein quality control network of B. subtilis are introduced.