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Increased dynamics in the 40–57 Ω-loop of the G41S variant of human cytochrome c promote its pro-apoptotic conformation

Karsisiotis, AI and Deacon, OM and Wilson, MT and Macdonald, C and Blumenschein, TMA and Moore, GR and Worrall, JAR (2016) 'Increased dynamics in the 40–57 Ω-loop of the G41S variant of human cytochrome c promote its pro-apoptotic conformation.' Scientific Reports, 6. ISSN 2045-2322

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Abstract

Thrombocytopenia 4 is an inherited autosomal dominant thrombocytopenia, which occurs due to mutations in the human gene for cytochrome c that results in enhanced mitochondrial apoptotic activity. The Gly41Ser mutation was the first to be reported. Here we report stopped-flow kinetic studies of azide binding to human ferricytochrome c and its Gly41Ser variant, together with backbone amide H/D exchange and 15N-relaxation dynamics using NMR spectroscopy, to show that alternative conformations are kinetically and thermodynamically more readily accessible for the Gly41Ser variant than for the wild-type protein. Our work reveals a direct conformational link between the 40?57??-loop in which residue 41 resides and the dynamical properties of the axial ligand to the heme iron, Met80, such that the replacement of glycine by serine promotes the dissociation of the Met80 ligand, thereby increasing the population of a peroxidase active state, which is a key non-native conformational state in apoptosis.

Item Type: Article
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Biological Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 12 Sep 2016 15:13
Last Modified: 07 Aug 2018 13:15
URI: http://repository.essex.ac.uk/id/eprint/17571

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