4lws | pdb_00004lws
EsxA : EsxB (SeMet) hetero-dimer from Thermomonospora curvata
Structural highlights
FunctionESXA_THECD May help regulate assembly and function of the type VII secretion system (T7SS) (PubMed:25865481). EsxA disassembles pre-formed EccC-EsxB multimers, possibly by making EccC-EsxA-EsxB trimers instead of EccC-EsxB-EsxB-EccC tetramers (PubMed:25865481).[1] Publication Abstract from PubMedMycobacterium tuberculosis and Staphylococcus aureus secrete virulence factors via type VII protein secretion (T7S), a system that intriguingly requires all of its secretion substrates for activity. To gain insights into T7S function, we used structural approaches to guide studies of the putative translocase EccC, a unique enzyme with three ATPase domains, and its secretion substrate EsxB. The crystal structure of EccC revealed that the ATPase domains are joined by linker/pocket interactions that modulate its enzymatic activity. EsxB binds via its signal sequence to an empty pocket on the C-terminal ATPase domain, which is accompanied by an increase in ATPase activity. Surprisingly, substrate binding does not activate EccC allosterically but, rather, by stimulating its multimerization. Thus, the EsxB substrate is also an integral T7S component, illuminating a mechanism that helps to explain interdependence of substrates, and suggests a model in which binding of substrates modulates their coordinate release from the bacterium. Substrates Control Multimerization and Activation of the Multi-Domain ATPase Motor of Type VII Secretion.,Rosenberg OS, Dovala D, Li X, Connolly L, Bendebury A, Finer-Moore J, Holton J, Cheng Y, Stroud RM, Cox JS Cell. 2015 Apr 23;161(3):501-12. doi: 10.1016/j.cell.2015.03.040. Epub 2015 Apr, 9. PMID:25865481[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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