Department of Biochemistry and Molecular Pharmacology
Life Sciences | Medicine and Health Sciences
Non-local hydrogen bonding interactions between main chain amide hydrogen atoms and polar side chain acceptors that bracket consecutive betaalpha or alphabeta elements of secondary structure in alphaTS from E. coli, a TIM barrel protein, have previously been found to contribute 4-6 kcal mol(-1) to the stability of the native conformation. Experimental analysis of similar betaalpha-hairpin clamps in a homologous pair of TIM barrel proteins of low sequence identity, IGPS from S. solfataricus and E. coli, reveals that this dramatic enhancement of stability is not unique to alphaTS. A survey of 71 TIM barrel proteins demonstrates a 4-fold symmetry for the placement of betaalpha-hairpin clamps, bracing the fundamental betaalphabeta building block and defining its register in the (betaalpha)(8) motif. The preferred sequences and locations of betaalpha-hairpin clamps will enhance structure prediction algorithms and provide a strategy for engineering stability in TIM barrel proteins.
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Citation: PLoS One. 2009 Sep 29;4(9):e7179. Link to article on publisher's site