title: Ca(2+)-induced stimulation of the membrane binding of Escherichia coli SecA and its association with signal peptides of secretory proteins.
abstract: Previously, it was found that Ca(2+) stimulates the intrinsic Escherichia coli SecA ATPase activity [Kim et al., FEBS Lett. 493 (2001) 12-16]. Now, we suggest that Ca(2+) is required for efficient interaction of SecA with membranes and the signal peptide of ribose-binding protein. When the amount of external Ca(2+) was enhanced, the amounts of membrane-bound SecA and its lipid/ATPase activity increased. In the presence of entrapped Ca(2+) in liposomes, the binding was also stimulated in a Ca(2+) concentration-dependent manner. The effect of Ca(2+) on the functional regulation of SecA was also evident in the presence of the signal peptides of secretory proteins, which the interaction of SecA with the signal peptide increased with increasing Ca(2+) concentration in the presence of membranes. However, other divalent cations including Mg(2+), Mn(2+), and Zn(2+) had inhibitory or no effect, suggesting a specific role of Ca(2+) in SecA interaction with lipid bilayers and signal peptides.
authors.affiliation: Department of Biochemistry, Chonnam National University, Gwangju, Republic of Korea. thahn@chonnam.ac.kr
authors.forename: Taeho
authors.initials: T
authors.lastname: Ahn
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Yun
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008051:Lipid Bilayers; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000502:physiology*; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; D026901:Membrane Transport Proteins; D021382:Protein Sorting Signals; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins; D002118:Calcium