title: Assembly of the type II secretion system such as found in Vibrio cholerae depends on the novel Pilotin AspS.
abstract: The Type II Secretion System (T2SS) is a molecular machine that drives the secretion of fully-folded protein substrates across the bacterial outer membrane. A key element in the machinery is the secretin: an integral, multimeric outer membrane protein that forms the secretion pore. We show that three distinct forms of T2SSs can be distinguished based on the sequence characteristics of their secretin pores. Detailed comparative analysis of two of these, the Klebsiella-type and Vibrio-type, showed them to be further distinguished by the pilotin that mediates their transport and assembly into the outer membrane. We have determined the crystal structure of the novel pilotin AspS from Vibrio cholerae, demonstrating convergent evolution wherein AspS is functionally equivalent and yet structurally unrelated to the pilotins found in Klebsiella and other bacteria. AspS binds to a specific targeting sequence in the Vibrio-type secretins, enhances the kinetics of secretin assembly, and homologs of AspS are found in all species of Vibrio as well those few strains of Escherichia and Shigella that have acquired a Vibrio-type T2SS.
authors: Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia.
authors: Rhys A
authors: RA
authors: Dunstan
authors: Eva
authors: E
authors: Heinz
authors: Lakshmi C
authors: LC
authors: Wijeyewickrema
authors: Robert N
authors: RN
authors: Pike
authors: Anthony W
authors: AW
authors: Purcell
authors: Timothy J
authors: TJ
authors: Evans
authors: Judyta
authors: J
authors: Praszkier
authors: Roy M
authors: RM
authors: Robins-Browne
authors: Richard A
authors: RA
authors: Strugnell
authors: Konstantin V
authors: KV
authors: Korotkov
authors: Trevor
authors: T
authors: Lithgow
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000502:physiology*; D001665:Binding Sites / Q000502:physiology; D019295:Computational Biology; D003460:Crystallization; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial; D007709:Klebsiella / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D018272:Porins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D012633:Secretin / Q000378:metabolism*; D013045:Species Specificity; D014734:Vibrio cholerae / Q000235:genetics / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D058947:Bacterial Secretion Systems; D018272:Porins; C422473:PulS protein, Klebsiella oxytoca; D012633:Secretin