Characterization of the mouse lanosterol 14alpha-demethylase (CYP51), a new member of the evolutionarily most conserved cytochrome P450 family

Abstract

Genes encoding sterol 14alpha-demethylases in eukaryotes and in Mycobacterium belong to the CYP51 family which is evolutionary the most conserved gene family within the cytochrome P450 superfamily. We have characterized a new member of this family, the mouse lanosterol 14alpha-demethylase, with the aim to study the in vivo role of this gene in spermatogenesis in mammals. The amino acid sequence of mouse Cyp51 is 96% identical to rat and 91% to human. Comparison of all known CYP51 proteins by the neighbor-joining method suggests that fungal and animal CYP51 genes arose from a common ancestral gene (98.3% probability) and interestingly, that plant and bacterial CYP51 genes share a common progenitor (88.8% probability). This suggests that the first CYP51 gene may have arisen in eukaryotes and has been transferred horizontally from plants to Mycobacterium. The mouse CYP51 gene is approximately 17-kb long and contains 10 exons. Transcription starts at several locations within the CpG island, which is characteristic for the TATA-less housekeeping genes. The mouse 5'-untranslated region (800 bp) contains putative cAMP-responsive elements (CRE), sterol regulatory elements (SRE) and GC-boxes at positions similar to human and rat, suggesting an evolutionary conserved mechanism of CYP51 transcriptional regulation in mammals. The mouse Cyp51 gene resides on chromosome 5, region A2, close to the centromere. No signals outside this region were detected as well as no evidence of processed pseudogenes using long PCR was found. This indicates that the mouse genome most likely lacks CYP51 processed pseudogenes.