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Title
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HisE11 and HisF8 provide bis-histidyl heme hexa-coordination in the globin domain of **Geobacter sulfurreducens** globin-coupled sensor
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Author
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Abstract
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| Among heme-based sensors, recent phylogenomic and sequence analyses have identified 34 globin coupled sensors (GCS), to which an aerotactic or gene-regulating function has been tentatively ascribed. Here, the structural and biochemical characterization of the globin domain of the GCS from Geobacter sulfurreducens (GsGCS162) is reported. A combination of X-ray crystallography (crystal structure at 1.5 Å resolution), UV-vis and resonance Raman spectroscopy reveals the ferric GsGCS162 as an example of bis-histidyl hexa-coordinated GCS. In contrast to the known hexa-coordinated globins, the distal heme-coordination in ferric GsGCS162 is provided by a His residue unexpectedly located at the E11 topological site. Furthermore, UV-vis and resonance Raman spectroscopy indicated that ferrous deoxygenated GsGCS162 is a penta-/hexa-coordinated mixture, and the heme hexa-to-penta-coordination transition does not represent a rate-limiting step for carbonylation kinetics. Lastly, electron paramagnetic resonance indicates that ferrous nitrosylated GsGCS162 is a penta-coordinated species, where the proximal HisF8-Fe bond is severed. |
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Language
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English
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Source (journal)
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Journal of molecular biology. - London
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Publication
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London
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2009
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ISSN
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0022-2836
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DOI
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10.1016/J.JMB.2008.12.023
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Volume/pages
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386
:1
(2009)
, p. 246-260
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ISI
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000263574300018
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Full text (Publisher's DOI)
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