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Preprotein‐controlled catalysis in the helicase motor of SecA
Author(s) -
Karamanou Spyridoula,
Gouridis Giorgos,
Papanikou Efrosyni,
Sianidis Giorgos,
Gelis Ioannis,
Keramisanou Dimitra,
Vrontou Eleftheria,
Kalodimos Charalampos G,
Economou Anastassios
Publication year - 2007
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601721
Subject(s) - biology , helicase , motor protein , genetics , microbiology and biotechnology , gene , rna , microtubule
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.