title: Specificity of SecYEG for PhoA precursors and SecA homologs on SecA protein-conducting channels.
abstract: Previous studies showed that Escherichia coli membranes depleted of SecYEG are capable of translocating certain precursor proteins, but not other precursors such as pPhoA, indicating a differential requirement for SecYEG. In this study, we examined the role of SecYEG in pPhoA translocation using a purified reconstituted SecA-liposomes system. We found that translocation of pPhoA, in contrast to that of pOmpA, requires the presence of purified SecYEG. A differential specificity of the SecYEG was also revealed in its interaction with SecA: EcSecYEG did not enhance SecA-mediated pOmpA translocation by purified SecA either from Pseudomonas aeruginosa or Bacillus subtilis. Neither was SecYEG required for eliciting ion channel activity, which could be opened by unfolded pPhoA or unfolded PhoA. Addition of the SecYEG complex did restore the specificity of signal peptide recognition in the ion-channel activity. We concluded that SecYEG confers specificity in interacting with protein precursors and SecAs.
authors.affiliation: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303.
authors.forename: Ying-Hsin
authors.initials: YH
authors.lastname: Hsieh
authors.affiliation: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303.
authors.forename: Bor-Ruei
authors.initials: BR
authors.lastname: Lin
authors.affiliation: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303.
authors.forename: Liyan
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303.
authors.forename: Hsiuchin
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303.
authors.forename: Chun
authors.initials: C
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084.
authors.forename: Sen-Fang
authors.initials: SF
authors.lastname: Sui
authors.affiliation: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303.
authors.forename: Phang C
authors.initials: PC
authors.lastname: Tai
mesh_terms: D000818:Animals; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D021381:Protein Transport; D000069816:SEC Translocation Channels; D014981:Xenopus
chemical_list: D029968:Escherichia coli Proteins; D000069816:SEC Translocation Channels
keywords: Channel activity; Protein-conducting channel; SecA-liposomes; SecYEG complex; pPhoA translocation