Conserved residues in the N-domain of the AAA+ chaperone ClpA regulate substrate recognition and unfolding.

摘要: Protein degradation in the cytosol of Escherichia coli is carried out by a variety different proteolytic machines, including ClpAP. The ClpA component hexameric AAA+ (ATPase associated with various cellular activities) chaperone that utilizes energy ATP to control substrate recognition and unfolding. precise role N-domains this process, however, remains elusive. Here, we have analysed five highly conserved basic residues N-domain monitoring binding, unfolding several substrates, short unstructured peptides, tagged untagged proteins. Interestingly, mutation three these within (H94, R86 R100) did not alter degradation. In contrast two arginine (R90 R131), flanking putative peptide-binding groove ClpA, specifically compromised ability unfold degrade selected substrates but prevent recognition, ClpS-mediated delivery or ClpP binding. contrast, tyrosine residue lining central pore hexamer was essential for all types analysed, both folded Taken together, data suggest structural elements, one other hexamer, which are required efficient some protein substrates.