6HIU

Cytochrome P460 from Methylococcus capsulatus (Bath)

Summary for 6HIU

• Entry DOI: 10.2210/pdb6hiu/pdb
• Related: 6HIH
• Descriptor: Cytochrome P460, HEME C, GLYCEROL, ... (5 entities in total)
• Functional Keywords: cytochrome, no, co, methanotroph, oxidoreductase
• Biological source: Methylococcus capsulatus (strain ATCC 33009 / NCIMB 11132 / Bath)
• Total number of polymer chains: 2
• Total formula weight: 36158.97

Authors

Adams, H.,Chicano, T.M.,Hough, M.A. (deposition date: 2018-08-31, release date: 2019-03-20, Last modification date: 2019-05-01)

Primary citation

Adams, H.R.,Krewson, C.,Vardanega, J.E.,Fujii, S.,Moreno, T.,Sambongi, Y.,Svistunenko, D.,Paps, J.,Andrew, C.R.,Hough, M.A.
One fold, two functions: cytochrome P460 and cytochromec'-beta from the methanotrophMethylococcus capsulatus(Bath).
Chem Sci, 10:3031-3041, 2019

PubMed Abstract: Nature is adept at utilising highly similar protein folds to carry out very different functions, yet the mechanisms by which this functional divergence occurs remain poorly characterised. In certain methanotrophic bacteria, two homologous pentacoordinate c-type heme proteins have been identified: a cytochrome P460 (cyt P460) and a cytochrome '-β (cyt cp-β). Cytochromes P460 are able to convert hydroxylamine to nitrous oxide (NO), a potent greenhouse gas. This reactivity is similar to that of hydroxylamine oxidoreductase (HAO), which is a key enzyme in nitrifying and methanotrophic bacteria. Cyt P460 and HAO both have unusual protein-heme cross-links, formed by a Tyr residue in HAO and a Lys in cyt P460. In contrast, cyts cp-β (the only known cytochromes ' with a β-sheet fold) lack this crosslink and appears to be optimized for binding non-polar molecules (including NO and CO) without enzymatic conversion. Our bioinformatics analysis supports the proposal that cyt cp-β may have evolved from cyt P460 a gene duplication event. Using high-resolution X-ray crystallography, UV-visible absorption, electron paramagnetic resonance (EPR) and resonance Raman spectroscopy, we have characterized the overall protein folding and active site structures of cyt cp-β and cyt P460 from the obligate methanotroph, (Bath). These proteins display a similar β-sheet protein fold, together with a pattern of changes to the heme pocket regions and localised tertiary structure that have converted a hydroxylamine oxidizing enzyme into a gas-binding protein. Structural comparisons provide insights relevant to enzyme redesign for synthetic enzymology and engineering of gas sensor proteins. We also show the widespread occurrence of cyts cp-β and characterise their phylogeny.

PubMed: 30996884
DOI: 10.1039/c8sc05210g

Experimental method

X-RAY DIFFRACTION (1.36 Å)