Repeat Motions and Backbone Flexibility in Designed Proteins with Different Numbers of Identical Consensus Tetratricopeptide Repeats
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- 作者：Cecilia Y. Cheng ; Virginia A. Jarymowycz ; Aitziber L. Cortajarena ; Lynne Regan ; Martin J. Stone
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：October 3, 2006
- 年：2006
- 卷：45
- 期：39
- 页码：12175 - 12183
- 全文大小：158K
- 年卷期：v.45,no.39(October 3, 2006)
- ISSN：1520-4995
文摘
The tetratricopeptide repeat (TPR) is a 34-residue helix-turn-helix motif that occurs as threeor more tandem repeats in a wide variety of proteins. We have determined the repeat motions and backbonefluctuations 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 eachrepeat within each TPR protein indicate that there is a high degree of motional correlation between differentrepeats in the same protein. This is consistent with the prevailing view that repeat proteins, such as CTPR2and CTPR3, behave as single cooperatively folded domains. The internal motions of backbone NH groupswere determined using the Lipari-Szabo model-free formalism. For most residues, there was a clearseparation between the influence of internal motion and the influence of global rotational tumbling on theobserved 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 indicatethat an addition of a TPR repeat to the C-terminus (before the solvation helix) of CTPR2 slightly reducesthe flexibility of the preceding helix.