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Exploring ligand recognition, selectivity and dynamics of TPR domains of chloroplast Toc64 and mitochondria Om64 from Arabidopsis thaliana
Author(s) -
Panigrahi Rashmi,
Whelan James,
Vrielink Alice
Publication year - 2014
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/jmr.2360
Subject(s) - tetratricopeptide , chloroplast , arabidopsis thaliana , co chaperone , chaperone (clinical) , translocon , biology , organelle , microbiology and biotechnology , arabidopsis , hsp90 , protein targeting , chloroplast membrane , mitochondrion , cytosol , biochemistry , heat shock protein , membrane protein , gene , membrane , thylakoid , medicine , pathology , mutant , enzyme
The study aims to gain insight into the mode of ligand recognition by tetratricopeptide repeat (TPR) domains of chloroplast translocon at the outer envelope of chloroplast (Toc64) and mitochondrial Om64, two paralogous proteins that mediate import of proteins into chloroplast and mitochondria, respectively. Chaperone proteins associate with precursor proteins in the cytosol to maintain them in a translocation competent conformation and are recognized by Toc64 and Om64 that are located on the outer membrane of the target organelle. Heat shock proteins (Hsp70) and Hsp90 are two chaperones, which are known to play import roles in protein import. The C‐termini of these chaperones are known to interact with the TPR domain of chloroplast Toc64 and mitochondrial Om64 in Arabidopsis thaliana ( At ). Using a molecular dynamics approach and binding energy calculations, we identify important residues involved in the interactions. Our findings suggest that the TPR domain from At Toc64 has higher affinity towards C‐terminal residues of Hsp70. The interaction occurs as the terminal helices move towards each other enclosing the cradle on interaction of At Hsp70 with the TPR domain. In contrast, the TPR domain from At Om64 does not discriminate between the C‐termini of Hsp70 and Hsp90. These binding affinities are discussed with respect to our knowledge of protein targeting and specificity of protein import into endosymbiotic organelles in plant cells. Copyright © 2014 John Wiley & Sons, Ltd.