Damage response protein 1 (Dap1) functions in the synthesis of carotenoids and sterols in Xanthophyllomyces dendrorhous

Cytochrome P450s (P450s) are heme-containing proteins involved in several cellular functions, including biosynthesis of steroidal hormones, detoxification of xenobiotic compounds, among others. Damage response protein 1 (Dap1) has been described as a positive regulator of P450s through protein-protein interactions in organisms such as Schizosaccharomyces pombe. Three P450s in the carotenogenic yeast Xanthophyllomyces dendrorhous have thus far been characterized: Cyp51 and Cyp61, which are involved in ergosterol biosynthesis, and CrtS (astaxanthin synthase), which is involved in biosynthesis of the carotenoid astaxanthin. In this work, we describe the X. dendrorhous DAP1 gene, deletion of which affected yeast pigmentation by decreasing the astaxanthin fraction and increasing the β-carotene (a substrate of CrtS) fraction, which is consistent with the known role of CrtS. We found that the proportion of ergosterol was also decreased in the Δdap1 mutant. However, even though the fractions of the end products of these two pathways (the synthesis of carotenoids and sterols) were decreased in the Δdap1 mutant, the transcript levels of genes from the P450 systems involved were higher than those in the wild-type strain. We demonstrate that Dap1 coimmunoprecipitates with these three P450s, suggesting that Dap1 interacts with these three proteins. We propose that Dap1 regulates the synthesis of astaxanthin and ergosterol in X. dendrorhous, probably by regulating the P450s involved in both biosynthetic pathways at the protein level. This work suggests a new role for Dap1 in the regulation of carotenoid biosynthesis in X. dendrorhous.