Heme sensing of the ChrS histidine kinase from Corynebacterium diphtheriae

到目前为止，人们一直认为白喉棒杆菌通过双组分信号转导系统的感受器激酶CHRS和反应调节器ChrA来利用宿主的血红素铁。尽管CHRS被预测为编码一个血红素传感器，但其感知机制仍未确定。在非离子洗涤剂存在下，对在大肠杆菌膜中表达的CHRS进行了增溶和纯化。蛋白脂质体和纳米盘中的CHRS蛋白可通过三磷酸腺苷催化血红素依赖的自磷酸化。其他金属卟啉和铁不能刺激激酶活性，这表明CHRS是一种特异的血红素感受器。这是细菌血红素敏感蛋白的首次功能重组。

It has been hitherto believed that Corynebacterium diphteriae conducts the sensor kinase, ChrS, and the response regulator, ChrA, of a two-component signal transduction system to utilize host heme iron. Although ChrS is predicted to encode a heme sensor, the sensing mechanism remains uncharacterized. ChrS expressed in Eshcherichia coli membranes was solubilized and purified in the presence of a non-ionic detergent. ChrS protein incorporated into proteoliposomes and nanodiscs catalyzed heme-dependent autophosphorylation by ATP. Other metalloporphyrins and iron did not stimulate kinase activity, suggesting that ChrS is a specific heme sensor. This is the first functional reconstitution of a bacterial heme-sensing protein.