Repeat Motions and Backbone Flexibility in Designed Proteins with Different Numbers of Identical Consensus Tetratricopeptide Repeats

Abstract

The tetratricopeptide repeat (TPR) is a 34-residue helix-turn-helix motif that occurs as three or more tandem repeats in a wide variety of proteins. We have determined the repeat motions and backbone fluctuations of proteins containing two or three consensus TPR repeats (CTPR2 and CPTR3, respectively) using 15N NMR relaxation measurements. Rotational diffusion tensors calculated from these data for each repeat within each TPR protein indicate that there is a high degree of motional correlation between different repeats in the same protein. This is consistent with the prevailing view that repeat proteins, such as CTPR2 and CTPR3, behave as single cooperatively folded domains. The internal motions of backbone NH groups were determined using the Lipari-Szabo model-free formalism. For most residues, there was a clear separation between the influence of internal motion and the influence of global rotational tumbling on the observed magnetic relaxation. The local internal motions are highly restricted in most of the helical elements, with slightly greater flexibility in the linker elements. Comparisons between CTPR2 and CTPR3 indicate that an addition of a TPR repeat to the C-terminus (before the solvation helix) of CTPR2 slightly reduces the flexibility of the preceding helix.

Evidence that the kinesin light chain domain contains tetratricopeptide repeat units

“…These fluctuations occurred for both the amber03 and charmm27 force fields. This finding is consistent with 15 N NMR relaxation measurements which show that the C-terminal residue of CTPR displays extensive fast internal motions (on a timescale of $1.5-2 ns) relative to the global rotational tumbling (Cheng et al, 2006). On the other hand, the 30 residue systems display no such large local movements.…”

“…NMR relaxation experiments suggest that individual TPRs are relatively rigid, with some motion between the loops that connect them. There is a high degree of motional correlation between different repeats in the same protein and this suggests that TPR monomers connected in tandem may function as a single cooperative unit (Cheng et al, 2006). Tandem TPR repeats form a right-handed superhelical conformation that creates an amphipathic channel (Blatch and Lassle, 1999).…”

Ligand Recognition by the TPR Domain of the Import Factor Toc64 from Arabidopsis thaliana

“…The H1 and H7 helices move backwards in order to expose the inner surface of the cradle for peptide binding. It is known that TPRs have a rigid conformation [26]. In contrast, this study provides evidence that the change in curvature by the concerted movement of secondary structural elements may be necessary for ligand binding.…”

“…The protein spans the membrane three times and positions the TPR domain facing the cytosol [20], [25]. The TPR domain of Toc64 is composed of three TPR repeats followed by a solvation or capping helix (Figure S1A) [26]. Association of Toc64 with preproteins was found to be chaperone mediated [25], [27].…”

Mapping the Energy Landscape of Repeat Proteins using NMR-detected Hydrogen Exchange

“…13,14 We have previously reported the design and characterization of a series of consensus TPR (CTPR) proteins. 9,[15][16][17] CTPR n proteins are built as arrays of multiple tandem copies (n) of a 34 amino acid consensus helix-turn-helix repeat terminated by a single "solvating" helix. All the CTPR proteins are stable and adopt the distinctive TPR fold (Fig.…”