Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China.
National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, People's Republic of China.
J Agric Food Chem. 2021 Nov 10;69(44):13113-13124. doi: 10.1021/acs.jafc.1c04777. Epub 2021 Oct 25.
The small subunit, ssPOXA3a/b, and the large subunit, POXA3, are indispensable components of typical heterodimeric laccase (Lacc2) in white rot fungi. However, the enzymatic and biological functions of ssPOXA3a/b remain unclear. The present study revealed that neither ssPOXA3a nor ssPOXA3b per se has a catalytic ability, whereas their combination with POXA3 (and especially ssPOXA3b) enhances the activity, thermostability, and pH stability of POXA3. In , there was no regulatory relationship between ssPOXA3a/b and POXA3 at the transcriptional level. However, overexpression had a negative feedback effect on transcription. By contrast, transcripts had no effect on any other laccase isoenzyme. Overexpression of resulted in small fungal pellets, thin mycelial walls, and facilitated laccase secretion. However, overexpression had no influence on pellet morphology. Collectively, this work elucidated the functions of ssPOXA3a/b and laid an empirical foundation for the development of high-yield laccase.
小亚基 ssPOXA3a/b 和大亚基 POXA3 是白腐真菌中典型异二聚体漆酶（Lacc2）的不可或缺组成部分。然而，ssPOXA3a/b 的酶学和生物学功能仍不清楚。本研究表明，ssPOXA3a 和 ssPOXA3b 本身均不具有催化能力，而它们与 POXA3 的组合（尤其是 ssPOXA3b）增强了 POXA3 的活性、热稳定性和 pH 稳定性。在转录水平上，ssPOXA3a/b 和 POXA3 之间没有调控关系。然而，过表达对转录具有负反馈作用。相比之下，转录物对任何其他漆酶同工酶均没有影响。过表达导致真菌小球体变小，菌丝壁变薄，漆酶分泌更容易。然而，过表达对小球体形态没有影响。总之，这项工作阐明了 ssPOXA3a/b 的功能，并为高产漆酶的开发奠定了经验基础。
