The extra fragment of the iron-sulfur protein (residues 96-107) of Rhodobacter sphaeroides cytochrome bc1 complex is required for protein stability.
The extra fragment of the iron-sulfur protein (residues 96-107) of Rhodobacter sphaeroides cytochrome bc1 complex is required for protein stability.
复制标题
球形红细菌细胞色素 bc1 复合物的铁硫蛋白的额外片段（残基 96-107）是蛋白质稳定性所必需的。
DOI：
10.1021/bi035378z
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Yu,Linda
中科院分区：
文献类型：
--
作者：
Xiao,Kunhong;Liu,Xiaoying;Yu,Chang-An;Yu,Linda
对来自不同来源的细胞色素bc 1复合物的Rieske铁硫蛋白（ISP）进行序列比对，发现细菌ISP含有一个额外的片段。为了研究该片段在细菌细胞色素b1复合物中的作用，产生并表征了在该片段的不同位置（残基96 - 107）缺失或单丙氨酸或多丙氨酸取代的表达His标记的细胞色素b1复合物的球形红细菌突变体。ISPΔ（96−107）、ISP（96−107）A和ISP（104−107）A突变体细胞，其中ISP的残基96−107缺失，残基96−107和104−107分别被丙氨酸取代，不能光合生长，并在由这些突变体细胞制备的胞质膜内显示nobc 1复合物活性。ISP（96−99）A的第96−99位残基被丙氨酸取代，其光合生长速率与补体细胞相当，而ISP（100−103）A的第100−103位残基被丙氨酸取代，其光合生长前的滞后期较长。从这两个突变体细胞制备的色素细胞有48%和9%的thebc 1活性在互补色素细胞中发现。这些突变体膜中bc 1活性的丧失（或降低）是由于ISP蛋白不稳定导致膜中ISP的缺乏（或降低），而不是由于突变影响细胞色素bc 1组装到膜中、细胞色素bc 1与细胞色素bc 1的结合亲和力或这两种细胞色素与ISP或亚基IV相互作用的能力。该片段中残基的重要性顺序为残基104 - 107 >残基100 - 103 >残基96 - 99。
Sequence alignment of the Rieske iron−sulfur protein (ISP) of cytochromebc1complex from various sources reveals that bacterial ISPs contain an extra fragment. To study the role of this fragment in bacterial cytochromebc1complex,Rhodobacter sphaeroidesmutants expressing His-tagged cytochromebc1complexes with deletion or single- or multiple-alanine substitution at various positions of this fragment (residues 96−107) were generated and characterized. The ISPΔ(96−107), ISP(96−107)A, and ISP(104−107)A mutant cells, in which residues 96−107 of ISP are deleted, and residues 96−107 and 104−107 are substituted with alanine, respectively, do not grow photosynthetically and show nobc1complex activity in intracytoplasmic membranes prepared from these mutant cells. The ISP(96−99)A, in which residues 96−99 are substituted with alanine, grows photosynthetically at a rate comparable to that of the complement cells, whereas ISP(100−103)A, in which residues 100−103 are substituted with alanine, has a longer lag period prior to photosynthetic growth. Chromatophores prepared from these two mutant cells have 48% and 9% of thebc1activity found in the complement chromatophores. The loss (or decrease) ofbc1activity in these mutant membranes results from a lack (or decrease) of ISP in the membrane due to ISP protein instability and not from mutations affecting the assembly of cytochromesbandc1into the membrane, the binding affinity of cytochromebto cytochromec1, or the ability of these two cytochromes to interact with ISP or subunit IV. The order of essentiality of residues in this fragment is residues 104−107 > residues 100−103 > residues 96−99.