Peptides derived from Kex2-processed repeat proteins are widely distributed and highly diverse in the Fungi kingdom
Peptides derived from Kex2-processed repeat proteins are widely distributed and highly diverse in the Fungi kingdom
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DOI：
10.1186/s40694-020-00100-5
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发表时间：
2020-07-01
影响因子：
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通讯作者：
Umemura, Maiko
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作者：
Umemura, Maiko
研究背景近年来，黄曲霉中一个与ustiloxin生物合成有关的基因簇被发现是子囊菌门中第一例核糖体合成和后修饰肽（ribosomally synthesized and post-conjunctionally modified peptide，RiPP）合成途径。RiPP由前体肽生物合成，前体肽经加工产生RiPP骨架（核心肽），用于进一步修饰，如甲基化和环化。Ustiloxin前体肽具有两个独特的特征：用于易位到内质网中的信号肽和在高尔基体中被Kex 2蛋白酶切割的高度重复的核心序列。根据这些特点，ustiloxin型RiPP前体肽或Kex 2加工重复蛋白（KEPs）的菌株属于真菌王国进行了计算调查，以调查的分布和推定的功能KEPs在真菌ecology.ResultsIn总数，7878 KEPs被检测到1345 1461株属于8门。每株菌的KEP平均数在子囊菌门为5.25个，在担子菌门为5.30个，但在放线菌纲（子囊菌门）中仅为1.35个，在银耳菌纲（担子菌门）中仅为1.00个。KEPs分为838个类型和2560个独立的KEPs，没有同源物。近200个类型分布于一个以上的属，14个类型分布于一个以上的门。这些类型包括酵母α交配因子和真菌信息素。22%KEP的基因伴随着DUF 3328结构域的蛋白质，这是必不可少的环化的核心肽的基因。含DUF 3328结构域的蛋白基因与KEP基因的平均距离为3.09个基因。几乎所有的基因（有三个例外）KEPs注释为酵母α-交配因子或真菌信息素没有伴随DUF 3328-域含有蛋白质genetes.ConclusionKEPs广泛分布在真菌王国，但它们的重复序列是高度多样性的。从这些结果和一些实例中，提出了一种假设，即KEP最初进化为未修饰的线性肽（例如，交配因素），然后出现了采用修饰的环状形式的那些（例如，毒素），以利用其强大的生物活性对抗捕食者和竞争微生物。
BackgroundRecently, a gene cluster responsible for biosynthesis of ustiloxin in Aspergillus flavus was identified as the first case of a ribosomally synthesized and post-translationally modified peptide (RiPP) synthetic pathway in Ascomycota. RiPPs are biosynthesized from precursor peptides, which are processed to produce the RiPP backbone (core peptides) for further modifications such as methylation and cyclization. Ustiloxin precursor peptide has two distinctive features: a signal peptide for translocation into the endoplasmic reticulum and highly repeated core sequences cleaved by Kex2 protease in the Golgi apparatus. On the basis of these characteristics, the ustiloxin-type RiPP precursor peptides or Kex2-processed repeat proteins (KEPs) in strains belonging to the Fungi kingdom were computationally surveyed, in order to investigate the distribution and putative functions of KEPs in fungal ecology.ResultsIn total, 7878 KEPs were detected in 1345 of 1461 strains belonging to 8 phyla. The average number of KEPs per strain was 5.25 in Ascomycota and 5.30 in Basidiomycota, but only 1.35 in the class Saccharomycetes (Ascomycota) and 1.00 in the class Tremellomycetes (Basidiomycota). The KEPs were classified into 838 types and 2560 stand-alone ones, which had no homologs. Nearly 200 types were distributed in more than one genus, and 14 types in more than one phylum. These types included yeast alpha-mating factors and fungal pheromones. Genes for 22% KEPs were accompanied by genes for DUF3328-domain-containing proteins, which are indispensable for cyclization of the core peptides. DUF3328-domain-containing protein genes were located at an average distance of 3.09 genes from KEP genes. Genes for almost all (with three exceptions) KEPs annotated as yeast alpha-mating factors or fungal pheromones were not accompanied by DUF3328-domain-containing protein genes.ConclusionKEPs are widely distributed in the Fungi kingdom, but their repeated sequences are highly diverse. From these results and some examples, a hypothesis was raised that KEPs initially evolved as unmodified linear peptides (e.g., mating factors), and then those that adopted a modified cyclic form emerged (e.g., toxins) to utilize their strong bioactivity against predators and competitive microorganisms.