Contribution of TyrB26 to the function and stability of insulin. Structure-activity relationships at a conserved hormone-receptor interface
- Author(s)
- Pandyarajan, V; Phillips, NB; Rege, NK; Lawrence, MC; Whittaker, J; Weiss, MA;
- Details
- Publication Year 2017,Volume 291,Issue #25,Page 12978-90
- Journal Title
- Journal of Biological Chemistry
- Publication Type
- Journal Article
- Abstract
- Crystallographic studies of insulin bound to receptor domains have defined the primary hormone-receptor interface. We investigated the role of TyrB26, a conserved aromatic residue at this interface. To probe the evolutionary basis for such conservation, we constructed 18 variants at B26. Surprisingly, non-aromatic polar or charged side chains (such as Glu, Ser, or ornithine; Orn) conferred high activity whereas the weakest-binding analogs contained Val, Ile and Leu substitutions. Modeling of variant complexes suggested that the B26 side chains pack within a shallow depression at the solvent-exposed periphery of the interface. This interface would disfavor large aliphatic side chains. The analogs with highest activity exhibited reduced thermodynamic stability, and heightened susceptibility to fibrillation. Perturbed self-assembly was also demonstrated in studies of the charged variants (Orn and Glu); indeed, the GluB26 analog exhibited aberrant aggregation in either the presence or absence of zinc ions. Thus, although TyrB26 is part of insulin's receptor-binding surface, our results suggest that its conservation has been enjoined by the aromatic ring's contributions to native stability and self-assembly. We envisage that such classical structural relationships reflect the implicit threat of toxic misfolding (rather than hormonal function at the receptor level) as a general evolutionary determinant of extant protein sequences.
- Publisher
- ASBMB
- Research Division(s)
- Structural Biology
- PubMed ID
- 27129279
- Publisher's Version
- https://doi.org/10.1074/jbc.M115.708347
- NHMRC Grants
- NHMRC/1005896, NHMRC/1058233,
- Terms of Use/Rights Notice
- Refer to copyright notice on published article.
Creation Date: 2016-06-15 08:01:04
Last Modified: 2018-07-04 03:08:37