Global co-ordination of protein translocation by the SecA IRA1 switch.
SecA, the dimeric ATPase subunit of protein translocase, contains a DEAD helicase catalytic core that binds to a regulatory C-terminal domain. We now demonstrate that IRA1, a conserved helix-loop-helix structure in the C-domain, controls C-domain conformation through direct interdomain contacts. C-domain conformational changes are transmitted to the DEAD motor and alter its conformation. These interactions establish DEAD motor/C-domain conformational cross-talk that requires a functional IRA1. IRA1-controlled binding/release cycles of the C-domain to the DEAD motor couple this cross-talk to protein translocation chemistries, i.e. DEAD motor affinities for ligands (nucleotides, preprotein signal peptides, and SecYEG, the integral membrane component of translocase) and ATP turnover. IRA1-mediated global co-ordination of SecA catalysis is essential for protein translocation.
Department of Biology, University of Crete, PO Box 1527, GR-71110 Iraklio, Crete, Greece.
Eleftheria
E
Vrontou
Spyridoula
S
Karamanou
Catherine
C
Baud
Giorgos
G
Sianidis
Anastassios
A
Economou
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000737:chemistry; D001426:Bacterial Proteins / Q000378:metabolism*; D002384:Catalysis; D020134:Catalytic Domain; D004252:DNA Mutational Analysis; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013050:Spectrometry, Fluorescence; D020349:Surface Plasmon Resonance; D013696:Temperature
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008024:Ligands; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C088616:SecG protein, E coli; C057841:SecY protein, E coli; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins