The cpx proteins of Escherichia coli K12. Structure of the cpxA polypeptide as an inner membrane component.
The cpx proteins of Escherichia coli K12. Structure of the cpxA polypeptide as an inner membrane component.
复制标题
大肠杆菌 K12 的 cpx 蛋白。
DOI：
10.1016/0022-2836(88)90013-7
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发表时间：
1988
影响因子：
5.6
通讯作者：
Silverman,PM
中科院分区：
文献类型：
--
作者：
Weber,RF;Silverman,PM
大肠杆菌K12的GenecpxA编码52,000MrCpxA多肽。这里报道的完整的cpxA核苷酸序列预测CpxA在其氨基末端的一半中含有两个延伸的疏水片段，因此可能是一种膜蛋白。使用alac-cpxAoperon融合质粒过量产生CpxA并通过免疫化学测定来检测多肽，我们表明CpxA在差异和等密度沉降过程中与细菌内膜分离。此外，用非离子去污剂提取粗膜可以溶解该蛋白质，但用 KCl 或 NaOH 则不能，这表明 Cpx 是一种内在的膜成分。对cpxA中的TnphoA插入的分析表明，CpxA的疏水片段之间的区域是周质的，而第二个这样的片段的羧基末端区域是细胞质的。基于这些结构数据，我们提出 CpxA 作为跨膜感觉蛋白发挥作用。 DNA序列数据还表明cpxA是操纵子的3'基因。
GenecpxAofEscherichia coliK12 encodes the 52,000MrCpxA polypeptide. The completecpxAnucleotide sequence, reported here, predicted that CpxA contains two extended, hydrophobic segments in its amino-terminal half and could therefore be a membrane protein. Using alac-cpxAoperon fusion plasmid to overproduce CpxA and an immunochemical assay to detect the polypeptide, we show that CpxA fractionated with the bacterial inner membrane during differential and isopycnic sedimentation. Moreover, the protein could be solubilized by extraction of crude membranes with non-ionic detergents but not with KCl or NaOH, indicating that Cpx is an intrinsic membrane component. Analysis of TnphoAinsertions incpxAindicated that the region between the hydrophobic segments of CpxA is periplasmic, whereas the region carboxy-terminal to the second such segment is cytoplasmic. Based on these structural data, we propose that CpxA functions as a trans-membrane sensory protein. The DNA sequence data also indicate thatcpxAis the 3′ gene of an operon.