Rede Avançada em Biologia Computacional (RABICÓ), Petrópolis, RJ, Brazil.
Centro de Biotecnologia, Programa de Pós-Graduação em Biologia Celular e Molecular (PPGBCM), Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Mol Genet Genomics. 2019 Aug;294(4):901-917. doi: 10.1007/s00438-019-01546-y. Epub 2019 Mar 28.
The Pr1 family of serine endopeptidases plays an important role in pathogenicity and virulence of entomopathogens such as Metarhizium anisopliae (Ascomycota: Hypocreales). These virulence factors allow for the penetration of the host cuticle, a vital step in the infective process of this fungus, which possesses 11 Pr1 isoforms (Pr1A through Pr1K). The family is divided into two classes with Class II (proteinase K-like) comprising 10 isoforms further split into three subfamilies. It is believed that these isoforms act synergistically and with other virulence factors, allowing pathogenicity to multiple hosts. As virulence coevolves through reciprocal selection with hosts, positive selection may lead to the evolution of new protease families or isoforms of extant ones that can withstand host defenses. This work tests this hypothesis in Class II Pr1 proteins, focusing on M. anisopliae, employing different methods for phylogenetic inference in amino acid and nucleotide datasets in multiple arrangements for Metarhizium spp. and related species. Phylogenies depict groups that match the taxonomy of their respective organisms with high statistical support, with minor discrepancies. Positively selected sites were identified in six out of ten Pr1 isoforms, most of them located in the proteolytic domain and spatially close to the catalytic residues. Moreover, there was evidence of functional divergence in the majority of pairwise comparisons. These results imply the existence of differential selective pressure acting on Pr1 proteins and a potential new isoform, likely affecting host specificities, virulence, or even adapting the organism to different host-independent lifestyles.
丝氨酸内肽酶家族在昆虫病原真菌如金龟子绿僵菌（子囊菌门：Hypocreales）的致病性和毒力中起着重要作用。这些毒力因子允许穿透宿主表皮，这是真菌感染过程中的一个重要步骤，该真菌拥有 11 种 Pr1 同工型（Pr1A 到 Pr1K）。该家族分为两类，其中 II 类（蛋白酶 K 样）包含 10 种同工型，进一步分为三个亚家族。据信这些同工型协同作用，并与其他毒力因子一起，使真菌对多种宿主具有致病性。由于毒力通过与宿主的相互选择而共同进化，正选择可能导致新的蛋白酶家族或现有蛋白酶家族的同工型的进化，这些蛋白酶家族或同工型能够抵御宿主防御。这项工作在 II 类 Pr1 蛋白中检验了这一假设，重点研究了金龟子绿僵菌，采用不同的方法在氨基酸和核苷酸数据集的多种排列中进行系统发育推断，以研究绿僵菌属和相关物种。系统发育树描绘了与各自生物体的分类学相匹配的群组，具有高度的统计支持，只有一些小的差异。在 10 种 Pr1 同工型中的 6 种中鉴定到了正选择位点，其中大多数位于蛋白水解结构域中，并且与催化残基空间上接近。此外，在大多数两两比较中都有功能分化的证据。这些结果意味着 Pr1 蛋白存在差异选择压力，并且可能存在新的同工型，这可能影响宿主特异性、毒力，甚至使生物体适应不同的宿主独立生活方式。
