title: The dispensability and requirement of SecA N-terminal aminoacyl residues for complementation, membrane binding, lipid-specific domains and channel activities.
abstract: SecA is an essential multifunctional protein for the translocation of proteins across bacterial membranes. Though SecA is known to function in the membrane, the detailed mechanism for this process remains unclear. In this study we constructed a series of SecA N-terminal deletions and identified two specific domains crucial for initial SecA/membrane interactions. The first small helix, the linker and part of the second helix (Δ2-22) were found to be dispensable for SecA activity in complementing the growth of a SecA ts mutant. However, deletions of N-terminal aminoacyl residues 23-25 resulted in severe progressive retardation of growth. Moreover, a decrease of SecA activity caused by N-terminal deletions correlated to the loss of SecA membrane binding, formation of lipid-specific domains and channel activity. All together, the results indicate that the N-terminal aminoacyl residues 23-25 play a critical role for SecA binding to membranes and that the N-terminal limit of SecA for activity is at the 25th amino acid.
authors.affiliation: Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Jeanetta Holley
authors.initials: JH
authors.lastname: Floyd
authors.affiliation: Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: You
authors.affiliation: Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Ying-Hsin
authors.initials: YH
authors.lastname: Hsieh
authors.affiliation: Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Yamin
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States.
authors.forename: Hsuichin
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States. Electronic address: biopct@gsu.edu.
authors.forename: Phang C
authors.initials: PC
authors.lastname: Tai
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D058635:Lipid-Linked Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D017384:Sequence Deletion
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D007473:Ion Channels; D058635:Lipid-Linked Proteins; D008563:Membrane Lipids; D026901:Membrane Transport Proteins; D010446:Peptide Fragments; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins
keywords: Channel activity; Complementation; Membrane binding; Protein translocation; SecA N-termini