Dissecting the Role of EpsE Subdomains in ATPase Activity and Type IISecretion in Vibrio cholerae.

Type II Secretion;ATPase;Vibrio Cholerae;Microbiology and Immunology;Science;Microbiology & Immunology

Patrick, Marcella D.Tsai, Billy ;

University of Michigan

关键词: Type II Secretion;    ATPase;    Vibrio Cholerae;    Microbiology and Immunology;    Science;    Microbiology & Immunology;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/84591/marcyp_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The Type II secretion (T2S) apparatus is required for the survival and fitness of Vibrio cholerae both in the human host as well as its natural aquatic environment due to its ability to secrete proteins such as cholera toxin and hydrolytic enzymes.This apparatus, which is widely distributed among Gram negative pathogens, is composed of at least 12 proteins and spans the entire cell envelope.The energy to support secretion through the T2S system is provided by an ATPase associated with this complex, EpsE.EpsE is homologous to many ATPases involved with other molecular trafficking machineries and is comprised of three distinct subdomains: the N-terminal domain (NTD), the C-terminal domain (CTD), and a tetracysteine coordinating zinc binding domain (CM).These studies demonstrate that the mechanism of ATP hydrolysis requires oligomerization of EpsE, which allows for the realignment of specific arginine residues from the NTD, CTD and the CTD of a neighboring subunit to form the active site.Replacement of any of these arginine residues in the active site or of residues within the subunit interface halts the activity of EpsE, suggesting conformational changes associated with the binding, hydrolysis and release of nucleotide must be precise.An additional arginine from the CM domain is also required to complete the active site, suggesting a role for all three domains in ATP hydrolysis and energizing the T2S machinery.Previous work has shown EpsE to interact with the T2S apparatus through its NTD with another T2S component, EpsL.The movement of the NTD in association with EpsL likely provides a means of transforming the energy from ATP hydrolysis into mechanical work to support T2S.This work provides further evidence that the CM domain may be involved in additional protein-protein contacts with either EpsL or another protein associated with the T2S machinery. It is conceivable that the CM domain may play a direct role in the regulation of ATPase activity as it is in prime position to connect the nucleotide binding pocket to other components of the T2S apparatus through protein-protein interactions.