An ATP-binding cassette-type cysteine transporter in Campylobacter jejuni inferred from the structure of an extracytoplasmic solute receptor protein
An ATP-binding cassette-type cysteine transporter in Campylobacter jejuni inferred from the structure of an extracytoplasmic solute receptor protein
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DOI：
10.1111/j.1365-2958.2005.04691.x
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发表时间：
2005-07-01
影响因子：
3.6
通讯作者：
Wilkinson, AJ
中科院分区：
文献类型：
--
作者：
Müller, A;Thomas, GH;Wilkinson, AJ
空肠弯曲菌是一种革兰氏阴性食源性病原体，与人类胃肠炎以及自身免疫性疾病格林巴利综合征有关。C.空肠是溶天冬氨酸的，因为它缺乏利用糖作为碳源的活性糖酵解途径。这表明对氨基酸作为营养物质的依赖性增加，并且这种生物体的基因组序列确实表明存在许多氨基酸摄取系统。Cj 0982，也称为CjaA，是一种假定的细胞质外溶质受体，用于一种这样的摄取系统以及主要的表面抗原和疫苗候选物。Cj 0982的晶体结构揭示了一种双结构域蛋白，在结构域之间的封闭腔中具有密度，这清楚地定义了结合的半胱氨酸配体的存在。荧光滴定实验用于证明Cj 0982紧密且特异性地结合半胱氨酸，K-d类似于10（-7）M，这与作为高亲和力转运蛋白的受体的作用一致。这些数据表明Cj 0982是ABC型半胱氨酸转运蛋白系统的结合蛋白组分，并且半胱氨酸摄取在C.空肠。
Campylobacter jejuni is a Gram-negative food-borne pathogen associated with gastroenteritis in humans as well as cases of the autoimmune disease Guillain Barre syndrome. C. jejuni is asaccharolytic because it lacks an active glycolytic pathway for the use of sugars as a carbon source. This suggests an increased reliance on amino acids as nutrients and indeed the genome sequence of this organism indicates the presence of a number of amino acid uptake systems. Cj0982, also known as CjaA, is a putative extracytoplasmic solute receptor for one such uptake system as well as a major surface antigen and vaccine candidate. The crystal structure of Cj0982 reveals a two-domain protein with density in the enclosed cavity between the domains that clearly defines the presence of a bound cysteine ligand. Fluorescence titration experiments were used to demonstrate that Cj0982 binds cysteine tightly and specifically with a K-d of similar to 10(-7) M consistent with a role as a receptor for a high- affinity transporter. These data imply that Cj0982 is the binding protein component of an ABC-type cysteine transporter system and that cysteine uptake is important in the physiology of C. jejuni.