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Short-lived metal-centered excited state initiates iron-methionine photodissociation in ferrous cytochrome c.

ABSTRACT: The dynamics of photodissociation and recombination in heme proteins represent an archetypical photochemical reaction widely used to understand the interplay between chemical dynamics and reaction environment. We report a study of the photodissociation mechanism for the Fe(II)-S bond between the heme iron and methionine sulfur of ferrous cytochrome c. This bond dissociation is an essential step in the conversion of cytochrome c from an electron transfer protein to a peroxidase enzyme. We use ultrafast X-ray solution scattering to follow the dynamics of Fe(II)-S bond dissociation and 1s3p (K?) X-ray emission spectroscopy to follow the dynamics of the iron charge and spin multiplicity during bond dissociation. From these measurements, we conclude that the formation of a triplet metal-centered excited state with anti-bonding Fe(II)-S interactions triggers the bond dissociation and precedes the formation of the metastable Fe high-spin quintet state.

SUBMITTER: Reinhard ME

PROVIDER: S-EPMC7889893 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Short-lived metal-centered excited state initiates iron-methionine photodissociation in ferrous cytochrome c.

Reinhard Marco E ME Mara Michael W MW Kroll Thomas T Lim Hyeongtaek H Hadt Ryan G RG Alonso-Mori Roberto R Chollet Matthieu M Glownia James M JM Nelson Silke S Sokaras Dimosthenis D Kunnus Kristjan K Driel Tim Brandt van TBV Hartsock Robert W RW Kjaer Kasper S KS Weninger Clemens C Biasin Elisa E Gee Leland B LB Hodgson Keith O KO Hedman Britt B Bergmann Uwe U Solomon Edward I EI Gaffney Kelly J KJ

Nature communications 20210217 1

The dynamics of photodissociation and recombination in heme proteins represent an archetypical photochemical reaction widely used to understand the interplay between chemical dynamics and reaction environment. We report a study of the photodissociation mechanism for the Fe(II)-S bond between the heme iron and methionine sulfur of ferrous cytochrome c. This bond dissociation is an essential step in the conversion of cytochrome c from an electron transfer protein to a peroxidase enzyme. We use ult ...[more]

PMID: 33597529

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Project description:A set of proteins that changed their levels of synthesis during growth of Acidithiobacillus ferrooxidans ATCC 19859 on metal sulfides, thiosulfate, elemental sulfur, and ferrous iron was characterized by using two-dimensional polyacrylamide gel electrophoresis. N-terminal amino acid sequencing and mass spectrometry analysis of these proteins allowed their identification and the localization of the corresponding genes in the available genomic sequence of A. ferrooxidans ATCC 23270. The genomic context around several of these genes suggests their involvement in the energetic metabolism of A. ferrooxidans. Two groups of proteins could be distinguished. The first consisted of proteins highly upregulated by growth on sulfur compounds (and downregulated by growth on ferrous iron): a 44-kDa outer membrane protein, an exported 21-kDa putative thiosulfate sulfur transferase protein, a 33-kDa putative thiosulfate/sulfate binding protein, a 45-kDa putative capsule polysaccharide export protein, and a putative 16-kDa protein of unknown function. The second group of proteins comprised those downregulated by growth on sulfur (and upregulated by growth on ferrous iron): rusticyanin, a cytochrome c(552), a putative phosphate binding protein (PstS), the small and large subunits of ribulose biphosphate carboxylase, and a 30-kDa putative CbbQ protein, among others. The results suggest in general a separation of the iron and sulfur utilization pathways. Rusticyanin, in addition to being highly expressed on ferrous iron, was also newly synthesized, as determined by metabolic labeling, although at lower levels, during growth on sulfur compounds and iron-free metal sulfides. During growth on metal sulfides containing iron, such as pyrite and chalcopyrite, both proteins upregulated on ferrous iron and those upregulated on sulfur compounds were synthesized, indicating that the two energy-generating pathways are induced simultaneously depending on the kind and concentration of oxidizable substrates available.

Dataset Information

Short-lived metal-centered excited state initiates iron-methionine photodissociation in ferrous cytochrome c.

Publications

Short-lived metal-centered excited state initiates iron-methionine photodissociation in ferrous cytochrome c.

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