College of Biological Science and Engineering, Fuzhou University, Fujian, China; The Key Laboratory of Marine Enzyme Engineering of Fujian Province, Fuzhou University, Fujian, China.
College of Biological Science and Engineering, Fuzhou University, Fujian, China; The Key Laboratory of Marine Enzyme Engineering of Fujian Province, Fuzhou University, Fujian, China.
Pestic Biochem Physiol. 2024 Aug;203:106015. doi: 10.1016/j.pestbp.2024.106015. Epub 2024 Jul 3.
Beauveria bassiana is a popular and eco-friendly biopesticide. During its pathogen-pest interaction, both N-acetylglucosamine (GlcNAc) catabolism and anabolism are crucial for nutrient supply and cell-wall construction. The initiation of GlcNAc metabolism relies on the catalysis of GlcNAc kinase, which has been extensively studied in the human pathogen Candida albicans. However, the physiological function of GlcNAc kinase remains poorly understood in entomopathogenic fungi. In the present study, a GlcNAc kinase homolog was identified and designated as BbHxk1 in B. bassiana. Deletion of BbHxk1 resulted in viable but reduced vegetative growth on various carbon sources. ΔBbHxk1 mutants displayed severe defects in cell wall integrity, making them more susceptible to cell wall stress cues. Furthermore, the absence of BbHxk1 resulted in an increase in conidial yield and blastospore production, and a faster rate of germination and filamentation, potentially attributed to higher intracellular ATP levels. BbHxk1 deficiency led to a reduction in the activities of cuticle-degrading enzymes, which might contribute to the attenuated pathogenicity specifically through cuticle penetration rather than hemocoel infection towards Galleria mellonella larvae. Being different from C. albicans Hxk1, which facultatively acts as a catalyzing enzyme and transcriptional regulator, BbHxk1 primarily acts as a catalyzing enzyme and metabolic regulator. The altered metabolomic profiling correlated with the phenotypic defects in ΔBbHxk1 mutants, further implicating a potential metabolism-dependent mechanism of BbHxk1 in mediating physiologies of B. bassiana. These findings not only unveil a novel role for GlcNAc kinase in B. bassiana, but also provide a solid theoretical basis to guide metabolic reprogramming in order to maintain or even enhance the efficiency of fungi for practical applications.
球孢白僵菌是一种流行且环保的生物农药。在其与病原体-害虫的相互作用过程中，N-乙酰葡萄糖胺（GlcNAc）的分解代谢和合成代谢对于养分供应和细胞壁构建都至关重要。GlcNAc 代谢的启动依赖于 GlcNAc 激酶的催化，该酶在人类病原体白念珠菌中已得到广泛研究。然而，GlcNAc 激酶在昆虫病原真菌中的生理功能仍知之甚少。在本研究中，鉴定并命名了球孢白僵菌中的 GlcNAc 激酶同源物为 BbHxk1。缺失 BbHxk1 导致在各种碳源上的营养生长仍然可行，但生长速度较慢。ΔBbHxk1 突变体在细胞壁完整性方面存在严重缺陷，使其对细胞壁应激信号更加敏感。此外，缺失 BbHxk1 导致分生孢子产量和芽生孢子产生增加，萌发和丝状生长速度加快，可能归因于细胞内 ATP 水平升高。BbHxk1 缺失导致角质层降解酶活性降低，这可能导致致病性减弱，特别是通过角质层穿透而不是血腔感染对家蚕幼虫的影响。与兼性作为催化酶和转录调节剂的白念珠菌 Hxk1 不同，BbHxk1 主要作为催化酶和代谢调节剂发挥作用。代谢组学分析与 ΔBbHxk1 突变体的表型缺陷相关，进一步表明 BbHxk1 可能通过代谢依赖性机制参与介导球孢白僵菌的生理功能。这些发现不仅揭示了 GlcNAc 激酶在球孢白僵菌中的新作用，而且为指导代谢重编程提供了坚实的理论基础，以维持甚至提高真菌在实际应用中的效率。
