Oliveira Eder Silva de, Junges Ângela, Sbaraini Nicolau, Andreis Fábio Carrer, Thompson Claudia Elizabeth, Staats Charley Christian, Schrank Augusto
Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Genet Mol Biol. 2018 Oct-Dec;41(4):843-857. doi: 10.1590/1678-4685-GMB-2017-0363. Epub 2018 Dec 10.
Cell walls are involved in manifold aspects of fungi maintenance. For several fungi, chitin synthesis, degradation and recycling are essential processes required for cell wall biogenesis; notably, the activity of β-N-acetylglucosaminidases (NAGases) must be present for chitin utilization. For entomopathogenic fungi, such as Metarhizium anisopliae, chitin degradation is also used to breach the host cuticle during infection. In view of the putative role of NAGases as virulence factors, this study explored the transcriptional profile and evolution of putative GH20 NAGases (MaNAG1 and MaNAG2) and GH3 NAGases (MaNAG3 and MaNAG4) identified in M. anisopliae. While MaNAG2 orthologs are conserved in several ascomycetes, MaNAG1 clusters only with Aspergilllus sp. and entomopathogenic fungal species. By contrast, MaNAG3 and MaNAG4 were phylogenetically related with bacterial GH3 NAGases. The transcriptional profiles of M. anisopliae NAGase genes were evaluated in seven culture conditions showing no common regulatory patterns, suggesting that these enzymes may have specific roles during the Metarhizium life cycle. Moreover, the expression of MaNAG3 and MaNAG4 regulated by chitinous substrates is the first evidence of the involvement of putative GH3 NAGases in physiological cell processes in entomopathogens, indicating their potential influence on cell differentiation during the M. anisopliae life cycle.
细胞壁参与真菌维持的多个方面。对于几种真菌而言，几丁质的合成、降解和循环利用是细胞壁生物合成所需的基本过程；值得注意的是，β-N-乙酰氨基葡萄糖苷酶（NAGases）的活性对于几丁质的利用是必需的。对于昆虫病原真菌，如绿僵菌，几丁质降解也被用于在感染过程中突破宿主表皮。鉴于NAGases作为毒力因子的假定作用，本研究探讨了在绿僵菌中鉴定出的假定GH20 NAGases（MaNAG1和MaNAG2）和GH3 NAGases（MaNAG3和MaNAG4）的转录谱和进化情况。虽然MaNAG2直系同源物在几种子囊菌中是保守的，但MaNAG1仅与曲霉属物种和昆虫病原真菌物种聚类。相比之下，MaNAG3和MaNAG4在系统发育上与细菌GH3 NAGases相关。在七种培养条件下评估了绿僵菌NAGase基因的转录谱，结果显示没有共同的调控模式，这表明这些酶在绿僵菌生命周期中可能具有特定作用。此外，由几丁质底物调节的MaNAG3和MaNAG4的表达是假定的GH3 NAGases参与昆虫病原生理细胞过程的首个证据，表明它们在绿僵菌生命周期中对细胞分化具有潜在影响。
