The ATPase activity of SecA is regulated by acidic phospholipids, SecY, and the leader and mature domains of precursor proteins.
The ATPase activity of SecA is stimulated by E. coli plasma membrane vesicles bearing SecY protein and a precursor protein such as proOmpA. This activity is termed "translocation ATPase". Liposomes alone can also stimulate SecA ATPase, but membrane proteins block this stimulation in native inner membranes. We define the stimulation of SecA ATPase by lipid as "SecA/lipid ATPase". SecA/lipid ATPase, translocation ATPase, and translocation into inner membrane vesicles require acidic phospholipids, suggesting an underlying unity of mechanism. ProOmpA and ATP stabilize liposome-bound SecA. Full SecA/lipid ATPase activity and stability are also seen when a mixture of a leader peptide and either OmpA or maltose binding protein (MBP) are added instead of proOmpA, while neither the leader peptide alone nor OmpA or MBP suffice. Cytosolic proteins in conjuction with a leader peptide are less active in this reaction, indicating that liposome-bound SecA protein recognizes both leader and mature domains.
Lill
R
R
Molecular Biology Institute, University of California, Los Angeles 90024-1570.
Dowhan
W
W
Wickner
W
W
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007700:Kinetics; D008081:Liposomes; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis; D010743:Phospholipids / Q000494:pharmacology*; D011498:Protein Precursors / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D000069816:SEC Translocation Channels
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008081:Liposomes; D010455:Peptides; D010743:Phospholipids; D011498:Protein Precursors; D021382:Protein Sorting Signals; D000069816:SEC Translocation Channels; C057841:SecY protein, E coli; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases