Nucleotide sequence of the btuCED genes involved in vitamin B12 transport in Escherichia coli and homology with components of periplasmic-binding-protein-dependent transport systems.
Nucleotide sequence of the btuCED genes involved in vitamin B12 transport in Escherichia coli and homology with components of periplasmic-binding-protein-dependent transport systems.
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参与大肠杆菌中维生素 B12 转运的 btuCED 基因的核苷酸序列以及与周质结合蛋白依赖性转运系统成分的同源性。
DOI：
10.1128/jb.167.3.928-934.1986
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发表时间：
1986
影响因子：
3.2
通讯作者：
Kadner,RJ
中科院分区：
文献类型：
--
作者：
Friedrich,MJ;deVeaux,LC;Kadner,RJ
大肠杆菌染色体btuCED区域的产物参与维生素B12跨细胞质膜的转运。测定携带himA基因的一部分和整个btuCED区的3，410碱基对HindIII-HincII DNA片段的核苷酸序列。比较开放阅读框的位置与转座子插入所定义的基因边界，可以将多肽产物分配给基因序列。btuC产物是分子量为31，683的高度非极性整合膜蛋白。疏水区域的分布表明存在许多跨膜结构域。btuD产品是一个相对极性，但膜相关的多肽先生27，088，并包含具有广泛的同源性的ATP结合外周膜成分的周质结合蛋白依赖性运输系统的片段。这种蛋白质的其他区域与外膜维生素B12受体的部分相似。btuE产物（Mr 20，474）似乎具有周质位置。它具有可溶性蛋白的平均亲水性，但缺乏明显的信号序列。Btu多肽的细胞位置以及结构和序列同源性表明这三种蛋白质与结合蛋白依赖性转运系统的组分相似。然而，对周质维生素B12结合蛋白的依赖性尚未得到证实。
The products of the btuCED region of the Escherichia coli chromosome participate in the transport of vitamin B12 across the cytoplasmic membrane. The nucleotide sequence of the 3,410-base-pair HindIII-HincII DNA fragment carrying a portion of the himA gene and the entire btuCED region was determined. Comparison of the location of the open reading frames with the gene boundaries defined by transposon insertions allowed the assignment of polypeptide products to gene sequences. The btuC product is a highly nonpolar integral membrane protein of molecular weight 31,683. The distribution of hydrophobic regions suggests the presence of numerous membrane-spanning domains. The btuD product is a relatively polar but membrane-associated polypeptide of Mr 27,088 and contains segments bearing extensive homology to the ATP-binding peripheral membrane constituents of periplasmic binding protein-dependent transport systems. Other regions of this protein are similar to portions of the outer membrane vitamin B12 receptor. The btuE product (Mr 20,474) appears to have a periplasmic location. It has the mean hydropathy of a soluble protein but lacks an obvious signal sequence. The cellular locations and structural and sequence homologies of the Btu polypeptides point to the similarity of these three proteins to components of binding protein-dependent transport systems. However, the dependence on a periplasmic vitamin B12-binding protein has not yet been demonstrated.