Title: Helicase Motif III in SecA is essential for coupling preprotein binding to translocation ATPase
Authors: Papanikou, Efrosyni ×
Karamanou, Spyridoula
Baud, Catherine
Sianidis, Giorgos
Frank, Miriam
Economou, Anastassios #
Issue Date: Aug-2004
Publisher: Published for EMBO by Oxford University Press
Series Title: EMBO Reports vol:5 issue:8 pages:807-11
Abstract: The SecA ATPase is a protein translocase motor and a superfamily 2 (SF2) RNA helicase. The ATPase catalytic core ('DEAD motor') contains the seven conserved SF2 motifs. Here, we demonstrate that Motif III is essential for SecA-mediated protein translocation and viability. SecA Motif III mutants can bind ligands (nucleotide, the SecYEG translocase 'channel', signal and mature preprotein domains), can catalyse basal and SecYEG-stimulated ATP hydrolysis and can be activated for catalysis. However, Motif III mutation specifically blocks the preprotein-stimulated 'translocation ATPase' at a step of the reaction pathway that lies downstream of ligand binding. A functional Motif III is required for optimal ligand-driven conformational changes and kinetic parameters that underlie optimal preprotein-modulated nucleotide cycling at the SecA DEAD motor. We propose that helicase Motif III couples preprotein binding to the SecA translocation ATPase and that catalytic activation of SF2 enzymes through Motif-III-mediated action is essential for both polypeptide and nucleic-acid substrates.
ISSN: 1469-221X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Non-KU Leuven Association publications
× corresponding author
# (joint) last author

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