Proteins are a main organic nitrogen source for microorganisms. Many heterotrophic microorganisms secrete extracellular proteases (ex-proteases) to efficiently decompose proteins into oligopeptides and amino acids when exterior proteins are required for growth. These ex-proteases not only play important roles in microbial nutrient acquisition or host infection but also contribute greatly to the global recycling of carbon and nitrogen. Moreover, may microbial ex-proteases have important applications in industrial, medical, and biotechnological areas. Therefore, uncovering the mechanisms by which microorganisms initiate the expression of ex-protease genes in response to exterior proteins is of great significance. In this review, the progress made in understanding the induction mechanisms of microbial ex-proteases in response to exterior proteins is summarized, with a focus on the inducer molecules, membrane sensors, and downstream pathways. Problems to be solved for better understanding of the induction mechanisms of microbial ex-proteases are also discussed.

中文翻译：

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响应外部蛋白质诱导微生物细胞外蛋白酶的机制。

蛋白质是微生物的主要有机氮源。当需要外部蛋白质生长时，许多异养微生物会分泌细胞外蛋白酶（蛋白酶），以有效地将蛋白质分解为寡肽和氨基酸。这些前蛋白酶不仅在微生物营养素获取或宿主感染中起重要作用，而且还为全球碳和氮的循环利用做出了巨大贡献。而且，微生物前蛋白酶可能在工业，医学和生物技术领域具有重要的应用。因此，揭示微生物响应外部蛋白质而启动前蛋白酶基因表达的机制具有重要意义。在这篇评论中 总结了了解微生物对前蛋白酶的诱导机制的研究进展，重点是诱导剂分子，膜传感器和下游途径。还讨论了需要解决的问题，以便更好地了解微生物前蛋白酶的诱导机制。