The dynamic action of SecA during the initiation of protein translocation.
695 - 705
MetadataShow full item record
The motor ATPase SecA drives protein secretion through the bacterial Sec complex. The PPXD (pre-protein cross-linking domain) of the enzyme has been observed in different positions, effectively opening and closing a clamp for the polypeptide substrate. We set out to explore the implicated dynamic role of the PPXD in protein translocation by examining the effects of its immobilization, either in the position occupied in SecA alone with the clamp held open or when in complex with SecYEG with the clamp closed. We show that the conformational change from the former to the latter is necessary for high-affinity association with SecYEG and a corresponding activation of ATPase activity, presumably due to the PPXD contacting the NBDs (nucleotide-binding domains). In either state, the immobilization prevents pre-protein transport. However, when the PPXD was attached to an alternative position in the associated SecYEG complex, with the clamp closed, the transport capability was preserved. Therefore large-scale conformational changes of this domain are required for the initiation process, but not for translocation itself. The results allow us to refine a model for protein translocation, in which the mobility of the PPXD facilitates the transfer of pre-protein from SecA to SecYEG.
AuthorsGold, VAM; Whitehouse, S; Robson, A; Collinson, I
- College Publications 
Showing items related by title, author, creator and subject.
Rowling, PJ; Sivertsson, EM; Perez-Riba, A; Main, ER; Itzhaki, LS (2015-10)Studying protein folding and protein design in globular proteins presents significant challenges because of the two related features, topological complexity and co-operativity. In contrast, tandem-repeat proteins have ...
Arbeloa, A; Garnett, J; Lillington, J; Bulgin, RR; Berger, CN; Lea, SM; Matthews, S; Frankel, G (2009-12)We investigated how the type III secretion system WxxxE effectors EspM2 of enterohaemorrhagic Escherichia coli, which triggers stress fibre formation, and SifA of Salmonella enterica serovar Typhimurium, which is involved ...
Structural analysis of SHARPIN, a subunit of a large multi-protein E3 ubiquitin ligase, reveals a novel dimerization function for the pleckstrin homology superfold. Stieglitz, B; Haire, LF; Dikic, I; Rittinger, K (2012-06-15)SHARPIN (SHANK-associated RH domain interacting protein) is part of a large multi-protein E3 ubiquitin ligase complex called LUBAC (linear ubiquitin chain assembly complex), which catalyzes the formation of linear ubiquitin ...