Stauff Devin L, Skaar Eric P
Contrib Microbiol. 2009;16:120-135. doi: 10.1159/000219376. Epub 2009 Jun 2.
The important human pathogen Staphylococcus aureus is able to satisfy its nutrient iron requirement by acquiring heme from host hemoglobin in the context of infection. However, heme acquisition exposes S. aureus to heme toxicity. In order to detect the presence of toxic levels of exogenous heme, S. aureus is able to sense heme through the heme sensing system (HssRS) two-component system. Upon sensing heme, HssRS directly regulates the expression of the heme-regulated ABC transporter HrtAB, which alleviates heme toxicity. Importantly, the inability to sense or respond to heme alters the virulence of S. aureus, highlighting the importance of heme sensing and detoxification to staphylococcal pathogenesis. Furthermore, potential orthologues of the Hss and Hrt systems are found in many species of Gram-positive bacteria, a possible indication that heme stress is a challenge faced by bacteria whose habitats include host tissues rich in heme.
重要的人类病原体金黄色葡萄球菌在感染过程中能够通过从宿主血红蛋白获取血红素来满足其营养铁需求。然而，获取血红素会使金黄色葡萄球菌暴露于血红素毒性之下。为了检测外源血红素的毒性水平，金黄色葡萄球菌能够通过血红素感应系统（HssRS）双组分系统感知血红素。一旦感知到血红素，HssRS会直接调节血红素调节的ABC转运蛋白HrtAB的表达，从而减轻血红素毒性。重要的是，无法感知或响应血红素会改变金黄色葡萄球菌的毒力，突出了血红素感应和解毒对葡萄球菌发病机制的重要性。此外，在许多革兰氏阳性细菌物种中发现了Hss和Hrt系统的潜在直系同源物，这可能表明血红素应激是栖息地包括富含血红素的宿主组织的细菌所面临的一个挑战。
