Department of Dermatology and Venerology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China; Department of Dermatology, Shenzhen Children's Hospital, Shenzhen, Guangdong, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China; Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
Microbiol Res. 2021 Mar;244:126668. doi: 10.1016/j.micres.2020.126668. Epub 2020 Dec 5.
Fonsecaea monophora, which is very similar to Fonsecaea pedrosoi in morphological features, has been commonly misdiagnosed as F. pedrosoi. Like F. pedrosoi, F. monophora has been also identified as a predominant pathogen of Chromoblastomycosis (CBM). Melanin has been recognized as a virulence factor in several fungi, however, it is still largely unknown about the biological role of melanin and how melanin is synthesized in F. monophora. In this study, we identified two putative polyketide synthase genes (pks), AYO21_03016 (pksA) and AYO21_10638, by searching against the genome of F. monophora. AYO21_03016 and AYO21_10638 were further targeted disrupted by Agrobacterium tumefaciens-mediated transformation (ATMT). We discovered that pksA gene was the major polyketide synthase required for melanin synthesis in F. monophora, rather than AYO21_10638. Phenotypic analysis showed that, knocking out of the pksA gene attenuated melanogenesis, growth rate, sporulation ability and virulence of F. monophora, as compared with wild-type and complementation strain (pksA-C). Furthermore, the ΔpksA mutant was confirmed to be more sensitive to the oxidative stress, extreme pH environment, and antifungal drugs including itraconazole (ITC), terbinafine (TER), and amphotericin B (AMB). Taken together, these findings enabled us to comprehend the role of pksA in regulating DHN-melanin pathway and its effect on the biological function of F. monophora.
外瓶霉（Fonsecaea monophora）在形态学特征上与佩氏瓶霉（Fonsecaea pedrosoi）非常相似，因此常被误诊为佩氏瓶霉。与佩氏瓶霉一样，外瓶霉也被确定为暗色丝孢霉病（Chromoblastomycosis，CBM）的主要病原体。黑色素已被认为是几种真菌中的毒力因子，但黑色素的生物学作用以及黑色素在外瓶霉中如何合成仍知之甚少。在这项研究中，我们通过搜索外瓶霉的基因组，鉴定了两个假定的聚酮合酶基因（pks），AYO21_03016（pksA）和 AYO21_10638。AYO21_03016 和 AYO21_10638 进一步通过农杆菌介导的转化（ATMT）靶向敲除。我们发现 pksA 基因是外瓶霉黑色素合成所必需的主要聚酮合酶，而不是 AYO21_10638。表型分析表明，与野生型和互补菌株（pksA-C）相比，pksA 基因敲除削弱了外瓶霉的黑色素生成、生长速率、产孢能力和毒力。此外，ΔpksA 突变体被证实对氧化应激、极端 pH 环境以及包括伊曲康唑（ITC）、特比萘芬（TER）和两性霉素 B（AMB）在内的抗真菌药物更敏感。总之，这些发现使我们能够理解 pksA 在调节 DHN-黑色素途径及其对 F. monophora 生物学功能的影响中的作用。
