Folding and Peptide Binding of TPR Motifs from SGT

Abstract

In eukaryotes, many proteins have evolved repetitive motifs to perform functions specific to their unique physiological demand. Mostly, these motifs have length between 20 and 40 residues and mediate a variety of distinctive protein-protein interactions [1]. These motifs often exist as a tandem array between 3 to 25 units to form a characteristic structure. Secondary structure of many of these motifs are found to be α-helices. For example, the armadillo repeat of 42 residues forms three α-helices, the ankyrin repeat of 33 residues adopts a β-hairpin-helix-loop-helix (β2α2) fold, the HEAT motif of 37–43 residues consists two antiparallel helices, and the tetratricopeptide repeat (TPR) motif of 34 residues forms an antiparallel couple of helices. Generally, these motifs have little conservation between their sequences, however, they all adopt compact conformations in all structures studied until now.