PhoH2 proteins are found in a very diverse range of microorganisms that span bacteria and archaea. These proteins are composed of two domains: an N-terminal PIN-domain fused with a C-terminal PhoH domain. Collectively this fusion functions as an RNA helicase and ribonuclease. In other genomic contexts, PINdomains and PhoHdomains are separate but adjacent suggesting association to achieve similar function. Exclusively among the mycobacteria, PhoH2 proteins are encoded in the genome with an upstream gene, phoAT, which is thought to play the role of an antitoxin (in place of the traditional VapB antitoxin that lies upstream of the 47 other PINdomains in the mycobacterial genome). This review examines PhoH2 proteins as a whole and describes the bioinformatics, biochemical, structural, and biological properties of the two domains that make up PhoH2: PIN and PhoH. We review the transcriptional regulators of phoH2 from two mycobacterial species and speculate on the function of PhoH2 proteins in the context of a Type II toxin-antitoxin system which are thought to play a role in the stress response in bacteria.

中文翻译：

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PhoH2蛋白偶联RNA解旋酶和RNAse活性。

在跨越细菌和古细菌的多种微生物中发现了PhoH2蛋白。这些蛋白质由两个域组成：与C端PhoH域融合的N端PIN域。该融合体总体上起RNA解旋酶和核糖核酸酶的作用。在其他基因组环境中，PIN域和PhoH域是分离的，但相邻提示关联以实现相似的功能。仅在分枝杆菌中，PhoH2蛋白在基因组中带有上游基因phoAT编码，phoAT被认为起着抗毒素的作用（代替了传统的VapB抗毒素，后者位于分枝杆菌基因组中其他47个PIN域的上游） 。这篇综述从整体上考察了PhoH2蛋白，并描述了组成PhoH2的两个结构域的生物信息学，生化，结构和生物学特性：PIN和PhoH。我们审查了来自两个分枝杆菌物种的phoH2的转录调节因子，并推测了在II型毒素-抗毒素系统的背景下PhoH2蛋白的功能，该系统被认为在细菌的应激反应中起作用。