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Assembly of the translocase motor onto the preprotein‐conducting channel
Author(s) -
Karamanou Spyridoula,
Bariami Vassiliki,
Papanikou Efrosyni,
Kalodimos Charalampos G.,
Economou Anastassios
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06402.x
Subject(s) - translocase , biology , periplasmic space , motor protein , biophysics , atpase , cytoplasm , biochemistry , microbiology and biotechnology , gene , enzyme , escherichia coli , microtubule , chromosomal translocation
Summary Bacterial protein secretion is catalysed by the SecYEG protein‐conducting channel complexed with the SecA ATPase motor. To gain insight into the SecA–SecYEG interaction we used peptide arrays, thermodynamic quantification, mutagenesis and functional assays. Our data reveal that: (i) SecA binds with low affinity on several, peripheral, exposed SecYEG sites. This largely electrostatic association is modulated by temperature and nucleotides. (ii) Binding sites cluster in five major binding ‘regions’: three that are exclusively cytoplasmic and two that reach the periplasm. (iii) Both the N‐terminal and c‐terminal regions of SecA participate in binding interactions and share some sites. (iv) Several of these sites are essential for translocase catalysis. Our data provide residue‐level dissection of the SecYEG–SecA interaction. Two models of assembly of SecA on dimeric SecYEG are discussed.