title: Substrates Control Multimerization and Activation of the Multi-Domain ATPase Motor of Type VII Secretion.
abstract: Mycobacterium 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.
authors: Division of Infectious Diseases, Department of Medicine, UCSF Medical Center, University of California, San Francisco, San Francisco, CA 94143-0654, USA.
authors: Oren S
authors: OS
authors: Rosenberg
authors: Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA.
authors: Dustin
authors: D
authors: Dovala
authors: School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors: Xueming
authors: X
authors: Li
authors: Division of Infectious Diseases, Department of Medicine, UCSF Medical Center, University of California, San Francisco, San Francisco, CA 94143-0654, USA; Achaogen, Inc., South San Francisco, CA 94080, USA.
authors: Lynn
authors: L
authors: Connolly
authors: Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA.
authors: Anastasia
authors: A
authors: Bendebury
authors: Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
authors: Janet
authors: J
authors: Finer-Moore
authors: Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Lawrence Berkeley National Laboratory, MS6-2100, Berkeley, CA 94720, USA.
authors: James
authors: J
authors: Holton
authors: Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
authors: Yifan
authors: Y
authors: Cheng
authors: Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
authors: Robert M
authors: RM
authors: Stroud
authors: Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA. Electronic address: jeffery.cox@ucsf.edu.
authors: Jeffery S
authors: JS
authors: Cox
mesh_terms: D039903:Actinobacteria / Q000201:enzymology* / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D058947:Bacterial Secretion Systems; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000378:metabolism / Q000472:pathogenicity; D013211:Staphylococcus aureus / Q000201:enzymology / Q000378:metabolism / Q000472:pathogenicity; D037521:Virulence Factors / Q000737:chemistry
chemical_list: D058947:Bacterial Secretion Systems; D037521:Virulence Factors; D000251:Adenosine Triphosphatases