Abstract：
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.
摘要：
球孢白僵菌是一种受欢迎的生态友好型生物农药。在其病原体-害虫相互作用期间，N-乙酰葡糖胺（GlcNAc）分解代谢和合成代谢对于营养供应和细胞壁构建至关重要。GlcNAc代谢的启动依赖于GlcNAc激酶的催化，已在人类病原体白色念珠菌中进行了广泛研究。然而,GlcNAc激酶的生理功能在昆虫病原真菌中仍然知之甚少。在本研究中,GlcNAc激酶同系物被鉴定,并被命名为BbHxk1。BbHxk1的缺失导致在各种碳源上有活力但减少的营养生长。ΔBbHxk1突变体在细胞壁完整性方面表现出严重缺陷，使它们更容易受到细胞壁应力信号的影响.此外，缺乏BbHxk1导致分生孢子产量和芽孢子产量增加，以及更快的发芽和成丝速度，可能归因于较高的细胞内ATP水平。BbHxk1缺乏导致表皮降解酶的活性降低，这可能导致致病性减弱，特别是通过角质层渗透而不是对GalleriaMellonella幼虫的血液coel感染。与白色念珠菌Hxk1不同，Hxk1兼作催化酶和转录调节因子，BbHxk1主要充当催化酶和代谢调节剂。改变的代谢组学分析与ΔBbHxk1突变体的表型缺陷相关，进一步暗示了BbHxk1在介导球孢芽孢杆菌生理方面的潜在代谢依赖性机制。这些发现不仅揭示了GlcNAc激酶在巴氏杆菌中的新作用，同时也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的效率，用于实际应用。
