Characterization of the Neurospora crassa DHN melanin biosynthetic pathway in developing ascospores and peridium cells
Characterization of the Neurospora crassa DHN melanin biosynthetic pathway in developing ascospores and peridium cells
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DOI：
10.1016/j.funbio.2018.10.005
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发表时间：
2019-01-01
期刊：
影响因子：
2.5
通讯作者：
Free, Stephen J.
中科院分区：
文献类型：
--
作者：
Ao, Jie;Bandyopadhyay, Sumit;Free, Stephen J.
粗糙脉孢菌含有合成黑色素的底物--二羟基萘的所有四种酶。我们发现dhn黑色素途径在粗毛拟青霉雌性发育过程中起作用，产生黑化的被膜和子囊孢子细胞壁。粗毛拟青霉含有一个聚酮合成酶(PER-1)、两个聚酮水解酶(PKH-1和PKH-2)、两个THN(四羟基萘)还原酶(PKR-1和PKR-2)和一个半胱氨酸脱水酶(SCY-1)。我们发现Per-1、PKH-1、PKR-1和SCY-1是子囊孢子黑化所必需的。我们还鉴定了通过自由基氧化聚合反应将dhn转化为黑色素的漆酶，并将其命名为LACM-1(黑色素形成漆酶-1)。在成熟的子囊膜中，LACM-1定位于周壁细胞间隙，而dhn途径酶定位于胞内小泡。我们提出了一个黑色素形成的模型，其中黑色素是在细胞壁空间内形成的，细胞壁结构类似于钢筋混凝土，细胞壁中包裹着葡聚糖、甲壳素和糖蛋白。这种排列提供了非常坚固和有弹性的细胞壁，并保护葡聚糖/甲壳素/糖蛋白基质免受酶的消化和自由基的破坏。(C)2018年英国真菌学会。爱思唯尔有限公司出版。保留所有权利。
Neurospora crassa contains all four enzymes for the synthesis of DHN (dihydroxynaphthalene), the substrate for melanin formation. We show that the DHN melanin pathway functions during N. crassa female development to generate melanized peridium and ascospore cell walls. N. crassa contains one polyketide synthase (PER-1), two polyketide hydrolases (PKH-1 and PKH-2), two THN (tetrahydroxynaphthalene) reductases (PKR-1 and PKR-2), and one scytalone dehydratase (SCY-1). We show that the PER-1, PKH-1, PKR-1 and SCY-1 are required for ascospoer melanization. We also identified the laccase that functions in the conversion of DHN into melanin via a free radical oxidative polymerization reaction, and have named the gene lacm-1 (laccase for melanin formation-1). In maturing perithecia, we show that LACM-1 is localized to the peridium cell wall space while the DHN pathway enzymes are localized to intracellular vesicles. We present a model for melanin formation in which melanin is formed within the cell wall space and the cell wall structure is similar to "reinforced concrete" with the cell wall glucan, chitin, and glycoproteins encased within the melanin polymer. This arrangement provides for a very strong and resilient cell wall and protects the glucan/chitin/glycoprotein matrix from digestion from enzymes and damage from free radicals. (C) 2018 British Mycological Society. Published by Elsevier Ltd. All rights reserved.