Deng Jun-Jin, Zhang Jia-Rui, Mao He-Hua, Zhang Ming-Shu, Lu Yi-Shan, Luo Xiao-Chun
Agro-Biological Gene Research Center, State Key Laboratory of Swine and Poultry Breeding Industry, Guangdong Academy of Agricultural Sciences, No. 20 Jinying Road, Tianhe, Guangzhou, Guangdong 510640, China.
School of Biology and Biological Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, PR China.
Int J Biol Macromol. 2025 Mar;293:139215. doi: 10.1016/j.ijbiomac.2024.139215. Epub 2024 Dec 26.
Vibrio-induced diseases pose a significant threat to shrimp aquaculture. While the mechanisms underlying Vibrio penetration of shrimp shells and the gastrointestinal tract remain unclear, this study implicates chitinases as critical virulence factors. Despite their inability to utilize chitin or shrimp shells as sole carbon and nitrogen sources, three major shrimp pathogens-V. alginolyticus, V. harveyi, and V. parahaemolyticus-thrive on chitin-supplemented media and efficiently degrade shrimp shells. Ten extracellular chitinases were identified and two clades, ChiA and ChiD, are conserved among three Vibrio, underscoring their critical role in chitin degradation by Vibrio. Furthermore, one or two copies of evolutionarily conserved ChtBD3 are identified, facilitating targeting chitin-rich structures as virulence factors. All chitinase genes rapidly respond to shrimp shell or colloidal chitin, particularly Vpchi90, which exhibited a 33,340.8-fold increase in expression, correlating with enhanced chitinase activity. To further investigate their functional role, rVaChi89 (ChiD) and rVpChi90 (ChiA) was successfully heterologous expressed in Bacillus subtilis, achieving yields of 0.58 and 0.91 U/mL, respectively. In vitro assay confirmed their ability to degrade shrimp shells into GlcNAc and chitooligomers, further supporting their role in host invasion. This study highlights Vibrio chitinases as critical virulence factors and potential drug targets, with implications for chitin waste recycling.
弧菌引发的疾病对虾类养殖构成重大威胁。虽然弧菌穿透虾壳和胃肠道的潜在机制尚不清楚，但本研究表明几丁质酶是关键的毒力因子。尽管三种主要的虾类病原体——溶藻弧菌、哈维氏弧菌和副溶血性弧菌——无法将几丁质或虾壳作为唯一的碳源和氮源利用，但它们在添加几丁质的培养基上生长良好，并能有效降解虾壳。研究鉴定出了十种细胞外几丁质酶，其中ChiA和ChiD两个进化枝在三种弧菌中保守，这突出了它们在弧菌降解几丁质过程中的关键作用。此外，还鉴定出了一到两个进化上保守的ChtBD3拷贝，有助于将富含几丁质的结构作为毒力因子进行靶向攻击。所有几丁质酶基因对虾壳或胶体几丁质都有快速反应，尤其是Vpchi90，其表达量增加了33340.8倍，与几丁质酶活性增强相关。为了进一步研究它们的功能作用，rVaChi89（ChiD）和rVpChi90（ChiA）在枯草芽孢杆菌中成功实现了异源表达，产量分别达到0.58和0.91 U/mL。体外试验证实了它们将虾壳降解为N-乙酰葡糖胺和几丁寡糖的能力，进一步支持了它们在宿主入侵中的作用。本研究强调弧菌几丁质酶是关键的毒力因子和潜在的药物靶点，对几丁质废物回收具有重要意义。
