Functional and structural characterisation of a viral cytochrome b5. Issue 22 (4th October 2013)

• Record Type: Journal Article
• Authors: 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.
• Is Part Of: FEBS letters. Volume 587:Issue 22(2013)
• Page Start: 3633
• Page End: 3639
• Publication Date: 2013-10-04
• Subjects: Cytochrome b5 -- Virus -- Crystallography -- P450 catalysis -- Ostreococcus tauri; Biochemistry -- Periodicals; Biophysics -- Periodicals; Molecular biology -- Periodicals; Biochimie -- Périodiques; Biochemistry; Biophysics; Molecular biology; Periodicals; 572.05
• DOI: 10.1016/j.febslet.2013.09.035
• Languages: English
• ISSNs: 0014-5793

Abstract

Abstract : 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. Abstract : Structure of a novel virus encoded cytochrome b 5 solved. The protein has identical spectral properties to purified human cytochrome b 5. The protein can substitute for yeast cytochrome b 5 in the P450 51 mediated sterol 14α‐demethylation. The protein lacks a hydrophobic C‐terminal anchor and is the first cytosolic cytochrome b 5 characterised. Suggests the importance of cytochrome b 5 metabolic activity at the extremes of cellular scale.