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Functional and structural characterisation of a viral cytochrome b 5
Author(s) -
Reid Emma L.,
Weynberg Karen D.,
Love John,
Isupov Michail N.,
Littlechild Jennifer A.,
Wilson William H.,
Kelly Steven L.,
Lamb David C.,
Allen Michael J.
Publication year - 2013
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2013.09.035
Subject(s) - cytochrome b5 , cytochrome p450 reductase , cytochrome b , cytochrome c1 , biochemistry , cytochrome c , biology , cytochrome , coenzyme q – cytochrome c reductase , chemistry , enzyme , gene , mitochondrion , mitochondrial dna
Cytochrome b 5 is a ubiquitous electron transport protein. The sequenced viral OtV‐2 genome, which infects Ostreococcus tauri , was predicted to encode a putative cytochrome b 5 enzyme. Using purified OtV‐2 cytochrome b 5 we confirm this protein has identical spectral properties to purified human cytochrome b 5 and additionally that the viral enzyme can substitute for yeast cytochrome b 5 in yeast cytochrome P450 51 mediated sterol 14α‐demethylation. The crystal structure of the OtV‐2 cytochrome b 5 enzyme reveals a single domain, comprising four β sheets, four α helices and a haem moiety, which is similar to that found in larger eukaryotic cytochrome proteins. As a product of a horizontal gene transfer event involving a subdomain of the host fumarate reductase‐like protein, OtV‐2 cytochrome b 5 appears to have diverged in function and is likely to have evolved an entirely new role for the virus during infection. Indeed, lacking a hydrophobic C‐terminal anchor, OtV‐2 encodes the first cytosolic cytochrome b 5 characterised. The lack of requirement for membrane attachment (in contrast to all other microsomal cytochrome b 5s) may be a reflection of the small size of the host cell, further emphasizes the unique nature of this virus gene product and draws attention to the potential importance of cytochrome b 5 metabolic activity at the extremes of cellular scale.