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Issue 26, 2012
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Changes in the heme ligation during folding of a Geobacter sulfurreducens sensor GSU0935

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Abstract

Ligand binding and substitution reactions are important for metalloprotein folding and function. The heme sensor of a methyl-accepting chemotaxis GSU0935 is a c-type cytochrome from the bacterium Geobacter sulfurreducens. The heme domain switches one of its axial ligands from H2O to a low-spin ligand, presumably Met, upon reduction. The study analyzes the stability and folding kinetics of the ferric domain. Guanidine hydrochloride denaturation yields the low-spin heme species arising from coordination of the ferric heme by non-native His residues. The population of the low-spin species further increases and then declines during protein refolding. Kinetics and mutational effects suggest that His54, from the N-terminal region of the domain, is the transient ligand to the heme. The capture and release of a non-native ligand within the compact partially-folded structures illustrates the flexibility of the heme environment in GSU0935, which may relate to the domain sensor function.

Graphical abstract: Changes in the heme ligation during folding of a Geobacter sulfurreducens sensor GSU0935

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Article information


Submitted
22 Jan 2012
Accepted
26 Mar 2012
First published
14 May 2012

Dalton Trans., 2012,41, 8022-8030
Article type
Paper

Changes in the heme ligation during folding of a Geobacter sulfurreducens sensor GSU0935

T. L. Freeman, Y. Hong, K. H. Schiavoni, D. M. Indika Bandara and E. V. Pletneva, Dalton Trans., 2012, 41, 8022
DOI: 10.1039/C2DT30166K

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