革兰氏阴性菌血红素载体蛋白Hemophore的结构及作用机制

Structural and functional reveal of the hemophore in Gram-negative bacteria

摘要:

血红素作为宿主体内最丰富的铁离子来源，是致病菌营养竞争的主要目标，尤其对于血红素自身合成途径部分丧失的细菌。革兰氏阴性菌血红素转运系统由血红素载体蛋白(Hemophore)、外膜血红素受体、TonB-ExbB-ExbD复合物、ABC转运体等组成。Hemophore是存在于细菌细胞膜上或分泌到胞外环境中的一种蛋白。它能从宿主血红素结合蛋白中捕获血红素并将其传递给外膜受体。目前，在不同革兰氏阴性菌中已发现3种类型的Hemophore，分别是HasA、HxuA和HmuY型。本文将详细描述这3种Hemophore捕获血红素及与外膜受体相互作用的机制，以期为进一步研究其他细菌血红素载体蛋白的功能及作用机制奠定基础。

Abstract:

Heme is the most abundant iron source in the host. It has been proven that heme was the main nutrient competition aim for the pathogenic bacteria, especially for the bacteria that is not able to synthesize heme. The heme acquisition system of Gram-negative bacteria is consist of hemophore, outer membrane heme receptor, TonB-ExbB-ExbD complex, periplasmic heme-binding proteins, ABC transporter and so on. Hemophore is a type of outer membrane or secreted protein that can extract heme from host hemoprotein and pass it to the outer membrane heme receptors. Up to date, three kinds of hemophores, HasA, HxuA and HmuY, have been identified in some Gram-negative bacteria. In this paper, we described the mechanism of these three types hemophore to capture heme and the interaction with outer membrane heme receptors in detail. It will be helpful for further understanding the function of hemophore and its working mechanism.