Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, México.
FEMS Microbiol Lett. 2012 Nov;336(2):113-21. doi: 10.1111/j.1574-6968.2012.02661.x. Epub 2012 Sep 18.
Short-chain monodomain family comprises pairs of membrane proteins of about 200 amino acid residues each that belong to the chromate ion transporter (CHR) superfamily. The short-chain CHR homologous pair Chr3N/Chr3C from Bacillus subtilis strain 168 confers chromate resistance only when both proteins are expressed. Membrane topology of the Chr3N and Chr3C proteins was determined in Escherichia coli by the analysis of translational fusions with reporter enzymes alkaline phosphatase and β-galactosidase. Each short-chain CHR protein was found to consist of five transmembrane segments with antiparallel orientation between them. The C terminus of Chr3N is located in the cytoplasm, whereas the C terminus of Chr3C is located in the periplasm. In silico analyses suggest that this antiparallel arrangement is shared by all protein members of the short-chain CHR3 subfamily and that the two Chr3N/Chr3C proteins might carry out distinct functions for the transport of chromate.
短链单域家族由每对约 200 个氨基酸残基的膜蛋白组成，属于铬酸盐转运体 (CHR) 超家族。枯草芽孢杆菌 168 株的短链 CHR 同源对 Chr3N/Chr3C 只有当两种蛋白都表达时才赋予铬酸盐抗性。通过与碱性磷酸酶和β-半乳糖苷酶报告酶的翻译融合分析，在大肠杆菌中确定了 Chr3N 和 Chr3C 蛋白的膜拓扑结构。每个短链 CHR 蛋白都由五个跨膜片段组成，它们之间呈反平行排列。Chr3N 的 C 末端位于细胞质中，而 Chr3C 的 C 末端位于周质中。计算机分析表明，这种反平行排列被短链 CHR3 亚家族的所有蛋白成员共享，并且两个 Chr3N/Chr3C 蛋白可能执行不同的功能以进行铬酸盐的运输。
