Article
- The EMBO Journal (2007) 26, 2904 - 2914
- doi:10.1038/sj.emboj.7601721
Published online: 24 May 2007
Subject Category:
Preprotein-controlled catalysis in the helicase motor of SecA
Spyridoula Karamanou1, Giorgos Gouridis1,2, Efrosyni Papanikou1, Giorgos Sianidis1, Ioannis Gelis3, Dimitra Keramisanou3, Eleftheria Vrontou1,2, Charalampos G Kalodimos3 and Anastassios Economou1,2
- Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology-Hellas, Crete, Greece
- Department of Biology, University of Crete, Crete, Greece
- Department of Chemistry, Rutgers University, Newark, NJ, USA
Correspondence to:
Anastassios Economou, Institute of Molecular Biology and Biotechnology, University of Crete, PO Box 1385, 71110 Iraklio, Crete, Greece. Tel.: +30 2810 391166/391167; Fax: +30 2810 391166; E-mail: aeconomo@imbb.forth.gr
Received 9 February 2007; Accepted 17 April 2007
Abstract
The cornerstone of the functionality of almost all motor proteins is the regulation of their activity by binding interactions with their respective substrates. In most cases, the underlying mechanism of this regulation remains unknown. Here, we reveal a novel mechanism used by secretory preproteins to control the catalytic cycle of the helicase 'DEAD' motor of SecA, the preprotein translocase ATPase. The central feature of this mechanism is a highly conserved salt-bridge, Gate1, that controls the opening/closure of the nucleotide cleft. Gate1 regulates the propagation of binding signal generated at the Preprotein Binding Domain to the nucleotide cleft, thus allowing the physical coupling of preprotein binding and release to the ATPase cycle. This relay mechanism is at play only after SecA has been previously 'primed' by binding to SecYEG, the transmembrane protein-conducting channel. The Gate1-controlled relay mechanism is essential for protein translocase catalysis and may be common in helicase motors.
Keywords:
- ATPase,
- DEAD motor,
- helicase,
- protein secretion
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