Li Juan, Guo Mei, Cao Yueqing, Xia Yuxian
School of Life Sciences, Chongqing University, Chongqing, China.
Chongqing Engineering Research Center for Fungal Insecticides, Chongqing, China.
Front Microbiol. 2020 May 5;11:849. doi: 10.3389/fmicb.2020.00849. eCollection 2020.
In fungi, peptidases play a crucial role in adaptability. At present, the roles of peptidases in ultraviolet (UV) and thermal tolerance are still unclear. In this study, a C69-family cysteine dipeptidase of the entomopathogenic fungus , MaPepDA, was expressed in . The purified enzyme had a molecular mass of 56-kDa, and displayed a high activity to dipeptide substrate with an optimal Ala-Gln hydrolytic activity at about pH 6.0 and 55°C. It was demonstrated that MaPepDA is an intracellular dipeptidase localized in the cytosol, and that it is expressed during the whole fungal growth. Disruption of the gene increased conidial germination, growth rate, and significantly improved the tolerance to UV-B and heat stress in . However, virulence and conidia production was largely unaffected in the Δ mutant. Digital gene expression data revealed that the Δ mutant had a higher UV-B and heat-shock tolerance compared to wild type by regulating transcription of sets of genes involved in cell surface component, cell growth, DNA repair, amino acid metabolism, sugar metabolism and some important signaling pathways of stimulation. Our results suggested that disruption of the could potentially improve the performance of fungal pesticides in the field application with no adverse effect on virulence and conidiation.
在真菌中，肽酶在适应性方面发挥着关键作用。目前，肽酶在紫外线（UV）耐受性和热耐受性方面的作用仍不清楚。在本研究中，昆虫病原真菌的一种C69家族半胱氨酸二肽酶MaPepDA在[具体表达系统未给出]中表达。纯化后的酶分子量为56 kDa，对二肽底物具有高活性，在pH约6.0和55°C时对Ala-Gln的水解活性最佳。结果表明，MaPepDA是一种定位于细胞质中的细胞内二肽酶，且在真菌整个生长过程中均有表达。[MaPepDA]基因的缺失增加了分生孢子的萌发率和生长速率，并显著提高了[具体真菌名称未给出]对UV-B和热胁迫的耐受性。然而，Δ突变体的毒力和分生孢子产量在很大程度上未受影响。数字基因表达数据显示，与野生型相比，Δ突变体通过调控参与细胞表面成分、细胞生长、DNA修复、氨基酸代谢、糖代谢以及一些重要刺激信号通路的基因转录，对UV-B和热休克具有更高的耐受性。我们的结果表明，[MaPepDA]基因的缺失可能会在不影响毒力和产孢的情况下，潜在地提高真菌农药在田间应用中的性能。
