School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland; email:
Annu Rev Microbiol. 2013;67:291-312. doi: 10.1146/annurev-micro-092412-155658. Epub 2013 Jun 26.
The response of eukaryotic microbes to low-oxygen (hypoxic) conditions is strongly regulated at the level of transcription. Comparative analysis shows that some of the transcriptional regulators (such as the sterol regulatory element-binding proteins, or SREBPs) are of ancient origin and probably regulate sterol synthesis in most eukaryotic microbes. However, in some fungi SREBPs have been replaced by a zinc-finger transcription factor (Upc2). Nuclear localization of fungal SREBPs is determined by regulated proteolysis, either by site-specific proteases or by an E3 ligase complex and the proteasome. The exact mechanisms of oxygen sensing are not fully characterized but involve responding to low levels of heme and/or sterols and possibly to levels of nitric oxide and reactive oxygen species. Changes in central carbon metabolism (glycolysis and respiration) are a core hypoxic response in some, but not all, fungal species. Adaptation to hypoxia is an important virulence characteristic of pathogenic fungi.
真核微生物对低氧（缺氧）条件的反应在转录水平上受到强烈调控。比较分析表明，一些转录调节剂（如固醇调节元件结合蛋白，或 SREBPs）具有古老的起源，可能在大多数真核微生物中调节固醇合成。然而，在一些真菌中，SREBPs 已被锌指转录因子（Upc2）取代。真菌 SREBPs 的核定位由受调控的蛋白水解决定，要么通过特定的蛋白酶，要么通过 E3 连接酶复合物和蛋白酶体。氧感应的确切机制尚未完全阐明，但涉及对低水平的血红素和/或固醇以及可能的一氧化氮和活性氧水平的反应。中央碳代谢（糖酵解和呼吸作用）的变化是一些但不是所有真菌物种对低氧的核心反应。对低氧的适应是致病真菌重要的毒力特征。
