title: Escherichia coli SecA truncated at its termini is functional and dimeric.
abstract: Terminal residues in SecA, the dimeric ATPase motor of bacterial preprotein translocase, were proposed to be required for function and dimerization. To test this, we generated truncation mutants of the 901aa long SecA of Escherichia coli. We now show that deletions of carboxy-terminal domain (CTD), the extreme CTD of 70 residues, or of the N-terminal nonapeptide or of both, do not compromise protein translocation or viability. Deletion of additional C-terminal residues upstream of CTD compromised function. Functional truncation mutants like SecA9-861 are dimeric, conformationally similar to SecA, fully competent for nucleotide and SecYEG binding and for ATP catalysis. Our data demonstrate that extreme terminal SecA residues are not essential for SecA catalysis and dimerization.
authors.affiliation: Department of Biology, Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology-Hellas and University of Crete, Iraklio, Crete, Greece.
authors.forename: Spyridoula
authors.initials: S
authors.lastname: Karamanou
authors.forename: Giorgos
authors.initials: G
authors.lastname: Sianidis
authors.forename: Giorgos
authors.initials: G
authors.lastname: Gouridis
authors.forename: Charalambos
authors.initials: C
authors.lastname: Pozidis
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Papanikolau
authors.forename: Efrosyni
authors.initials: E
authors.lastname: Papanikou
authors.forename: Anastassios
authors.initials: A
authors.lastname: Economou
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D006868:Hydrolysis; D007473:Ion Channels / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009711:Nucleotides / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D021381:Protein Transport; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D007473:Ion Channels; D026901:Membrane Transport Proteins; D009711:Nucleotides; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins