Emri Tamás, Molnár Zsolt, Szilágyi Melinda, Pócsi István
Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
Appl Biochem Biotechnol. 2008 Dec;151(2-3):211-20. doi: 10.1007/s12010-008-8174-7. Epub 2008 Mar 4.
In terms of cell physiology, autolysis is the centerpiece of carbon-starving fungal cultures. In the filamentous fungus model organism Aspergillus nidulans, the last step of carbon-starvation-triggered autolysis was the degradation of the cell wall of empty hyphae, and this process was independent of concomitantly progressing cell death at the level of regulation. Autolysis-related proteinase and chitinase activities were induced via FluG signaling, which initiates sporulation and inhibits vegetative growth in surface cultures of A. nidulans. Extracellular hydrolase production was also subjected to carbon repression, which was only partly dependent on CreA, the main carbon catabolite repressor in this fungus. These data support the view that one of the main functions of autolysis is supplying nutrients for sporulation, when no other sources of nutrients are available. The divergent regulation of cell death and cell wall degradation provides the fungus with the option to keep dead hyphae intact to help surviving cells to absorb biomaterials from dead neighboring cells before these are released into the extracellular space. The industrial significance of these observations is also discussed in this paper.
就细胞生理学而言，自溶是碳饥饿真菌培养物的核心。在丝状真菌模式生物构巢曲霉中，碳饥饿引发的自溶的最后一步是空菌丝细胞壁的降解，并且这个过程在调控水平上与同时发生的细胞死亡无关。自溶相关蛋白酶和几丁质酶活性通过FluG信号诱导，FluG信号启动构巢曲霉表面培养物中的孢子形成并抑制营养生长。细胞外水解酶的产生也受到碳代谢阻遏，这仅部分依赖于该真菌中的主要碳分解代谢物阻遏物CreA。这些数据支持这样一种观点，即自溶的主要功能之一是在没有其他营养来源时为孢子形成提供营养。细胞死亡和细胞壁降解的不同调控为真菌提供了一种选择，即保持死亡的菌丝完整，以帮助存活的细胞在这些物质释放到细胞外空间之前从死亡的相邻细胞中吸收生物材料。本文还讨论了这些观察结果的工业意义。
