Department of Microbiology, Dokkyo Medical University School of Medicine, Tochigi 321-0293, Japan.
Hirara Clinic, Okinawa 906-0012, Japan.
Med Mycol. 2021 Sep 3;59(9):855-863. doi: 10.1093/mmy/myab012.
Prototheca spp. are achlorophyllous algae, ubiquitous in nature. An increasing number of human and animal cases of Prototheca infection (protothecosis) are reported, and antifungal azoles, which inhibit sterol 14α-demethylase (CYP51/ERG11) involved in ergosterol biosynthesis, have empirically been used for the treatment of protothecosis. Although Prototheca, like fungi, has ergosterol in the cell membrane, efficacy of the antifungal azoles in the treatment of protothecosis is controversial. For investigating the interaction of azole drugs with Prototheca CYP51/ERG11, the CYP51/ERG11 genomic genes of four strains of P. wickerhamii and one strain each of P. cutis and P. miyajii were isolated and characterized in this study. Compared with the CYP51/ERG11 gene of chlorophyllous Auxenochlorella Protothecoides, it is possible that ProtothecaCYP51/ERG11 gene, whose exon-intron structure appeared to be species-specific, lost introns associated with the loss of photosynthetic activity. Analysis of the deduced amino acid sequences revealed that Prototheca CYP51/ERG11 and fungal CYP51/ERG11 are phylogenetically distant from each other although their overall structures are similar. Our basic in silico studies predicted that antifungal azoles could bind to the catalytic pocket of Prototheca CYP51/ERG11. It was also suggested that amino acid residues away from the catalytic pocket might affect the drug susceptibility. The results of this study may provide useful insights into the phylogenetic taxonomy of Prototheca spp. in relationship to the CYP51/ERG11 structure and development of novel therapeutic drugs for the treatment of protothecosis.
Cases of infection by microalgae of Prototheca species are increasing. However, effective treatment has not been established yet. In this study, gene and structure of Prototheca's CYP51/ERG11, an enzyme which might serve as a target for therapeutic drugs, were characterized for the first time.
Prototheca 属是一种不含叶绿素的藻类，广泛存在于自然界中。越来越多的人类和动物感染 Prototheca （ protothecosis ）的病例报告，抗真菌唑类药物，抑制固醇 14α-去甲基酶（ CYP51 / ERG11 ）参与麦角固醇生物合成，已被经验用于治疗 protothecosis 。虽然 Prototheca 与真菌一样，在细胞膜中有麦角固醇，但唑类药物治疗 protothecosis 的疗效仍存在争议。为了研究唑类药物与 Prototheca CYP51 / ERG11 的相互作用，本研究分离并鉴定了四株 P. wickerhamii 和一株 P. cutis 和一株 P. miyajii 的 CYP51 / ERG11 基因组基因。与含叶绿素的 Auxenochlorella Protothecoides 的 CYP51 / ERG11 基因相比， Prototheca CYP51 / ERG11 基因的外显子 - 内含子结构似乎具有种特异性，可能与失去光合作用活性有关的内含子丢失。推导的氨基酸序列分析表明， Prototheca CYP51 / ERG11 和真菌 CYP51 / ERG11 虽然结构相似，但在系统发育上彼此相距甚远。我们的基础计算机模拟研究预测，抗真菌唑类药物可以与 Prototheca CYP51 / ERG11 的催化口袋结合。还表明远离催化口袋的氨基酸残基可能影响药物敏感性。这项研究的结果可能为 Prototheca 属的系统发育分类学提供有用的见解，与 CYP51 / ERG11 结构有关，并为 protothecosis 的治疗开发新的治疗药物。
感染 Prototheca 属微藻的病例正在增加。然而，尚未建立有效的治疗方法。在这项研究中，首次对 Prototheca 的 CYP51 / ERG11 基因和结构进行了表征，该酶可能是治疗药物的靶点。
