Denatured State Conformational Biases in Three-Helix Bundles Containing Divergent Sequences Localize near Turns and Helix Capping Residues.
Denatured State Conformational Biases in Three-Helix Bundles Containing Divergent Sequences Localize near Turns and Helix Capping Residues.
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DOI：
10.1021/acs.biochem.1c00400
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发表时间：
2021-10-19
期刊：
影响因子：
2.9
通讯作者：
Bowler BE
中科院分区：
文献类型：
--
作者：
Leavens MJ;Spang LE;Cherney MM;Bowler BE
Rhodopseudomonas palustris cytochrome c′, a four-helix bundle, and the second ubiquitin-associated domain, UBA(2), a three-helix bundle from the human homolog of yeast Rad23, HHR23A, deviate from random coil behavior under denaturing conditions in a fold-specific manner. The random coil deviations in each of these folds occur near interhelical turns and loops in their tertiary structures. Here, we examine an additional three-helix bundle with an identical fold to UBA(2), but a highly divergent sequence, the first ubiquitin-associated domain, UBA(1), of HHR23A. We use histidine-heme loop formation methods, employing eight single histidine variants, to probe for denatured state conformational bias of a UBA(1) domain fused to the N-terminus of iso-1-cytochrome c (iso-1-Cytc). Guanidine hydrochloride (GuHCl) denaturation shows that the iso-1-Cytc domain unfolds first, followed the UBA(1) domain. Denatured state (4 M and 6 M GuHCl ) histidine-heme loop formation studies show that as the size of the histidine-heme loop increases, loop stability decreases, as expected for the Jacobson-Stockmayer relationship. However, loops formed with His35, His31 and His15, of UBA(1), are 0.6 – 1.1 kcal/mol more stable than expected from the Jacobson-Stockmayer relationship, confirming the importance of deviations of the denatured state from random coil behavior near interhelical turns of helical domains, for facilitating folding to the correct topology. For UBA(1) and UBA(2), hydrophobic clusters on either side of the turns partially explain deviations from random coil behavior, however, helix capping also appears to be important.
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DOI：
10.1073/pnas.96.17.9597
发表时间：
1999-08-17
影响因子：
11.1
作者：
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通讯作者：
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影响因子：
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影响因子：
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DOI：
10.1073/pnas.0501773102
发表时间：
2005-09-20
影响因子：
11.1
作者：
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通讯作者：
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影响因子：
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作者：
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