Structural highlights
FunctionPublication Abstract from PubMedCytochrome b5 is a ubiquitous electron transport protein. The sequenced viral OtV-2 genome, which infects Ostreococcus tauri, was predicted to encode a putative cytochrome b5 enzyme. Using purified OtV-2 cytochrome b5 we confirm this protein has identical spectral properties to purified human cytochrome b5 and additionally that the viral enzyme can substitute for yeast cytochrome b5 in yeast cytochrome P450 51 mediated sterol 14alpha-demethylation. The crystal structure of the OtV-2 cytochrome b5 enzyme reveals a single domain, comprising four beta sheets, four alpha 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 b5 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 b5 characterised. The lack of requirement for membrane attachment (in contrast to all other microsomal cytochrome b5s) 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 b5 metabolic activity at the extremes of cellular scale. Functional and structural characterisation of a viral cytochrome b5.,Reid EL, Weynberg KD, Love J, Isupov MN, Littlechild JA, Wilson WH, Kelly SL, Lamb DC, Allen MJ FEBS Lett. 2013 Nov 15;587(22):3633-9. doi: 10.1016/j.febslet.2013.09.035. Epub, 2013 Oct 4. PMID:24100138[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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