Lamb David C, Goldstone Jared V, Belhaouari Djamal Brahim, Andréani Julien, Farooqi Ayesha, Allen Michael J, Kelly Steven L, La Scola Bernard, Stegeman John J
Faculty of Medicine, Health and Life Sciences, Swansea University, Swansea, Wales, SA2 8PP, UK.
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543, USA.
Npj Viruses. 2025 Feb 11;3(1):8. doi: 10.1038/s44298-025-00091-3.
Cytochrome b5 is an electron transport protein found in eukaryotes and bacteria, and plays roles in energy production, lipid biosynthesis and cytochrome P450 biochemistry. Here we report that genes for cytochrome b5 occur broadly among viruses in the class Megaviricetes isolated from the deep ocean, freshwater and terrestrial sources, and human patients. Transcriptional analysis showed that Mimivirus bradfordmassiliense cytochrome b5 is expressed in the host and has characteristic spectral properties. Viral cytochrome b5s have either a unique N-terminal transmembrane anchor or are predicted to be soluble proteins. Virus cytochrome b5 proteins share 45-95% sequence identity with one another but no more than 25% identity with that in Acanthamoeba castellanii, a host for many giant viruses. Thus, the origin of cytochrome b5 genes in giant viruses remains unknown. Our findings raise questions regarding the evolution and diversity of cytochrome b5, and about the origin of viral haemoproteins in general.
细胞色素b5是一种在真核生物和细菌中发现的电子传递蛋白，在能量产生、脂质生物合成和细胞色素P450生物化学过程中发挥作用。在此，我们报告称，细胞色素b5基因广泛存在于从深海、淡水、陆地来源以及人类患者中分离出的巨型病毒纲病毒中。转录分析表明，布拉德福德马赛巨型病毒的细胞色素b5在宿主中表达，并具有特征性光谱特性。病毒细胞色素b5要么具有独特的N端跨膜锚定结构，要么被预测为可溶性蛋白。病毒细胞色素b5蛋白彼此之间的序列同一性为45%至95%，但与许多巨型病毒的宿主——卡氏棘阿米巴中该蛋白的同一性不超过25%。因此，巨型病毒中细胞色素b5基因的起源仍然未知。我们的发现引发了关于细胞色素b5的进化和多样性以及一般病毒血红蛋白起源的问题。
