Mazur Andrzej, Marczak Małgorzata, Król Jarosław E, Skorupska Anna
Department of General Microbiology, Institute of Microbiology and Biotechnology, University of M. Curie-Skłodowska, 19 Akademicka St., 20-033, Lublin, Poland.
Arch Microbiol. 2005 Oct;184(1):1-10. doi: 10.1007/s00203-005-0018-z. Epub 2005 Nov 3.
An identified pssL gene is yet another one, besides the pssT, pssN and pssP genes, encoding for a protein engaged in polysaccharide polymerization and export in Rhizobium leguminosarum bv. trifolii strain TA1 (RtTA1). Amino acid sequence similarity and hypothetical protein secondary structure placed the PssL protein within Wzx (RfbX) translocases with putative flippase function that belong to the polysaccharide specific transport (PST) family. The predicted secondary structure of the PssL membrane protein was examined with a series of PssL-PhoA and PssL-LacZ translational fusions. The results support the hypothesis of PssL being a member of PST protein family comprising transporters with 12 membrane spanning segments and amino and carboxyl termini located in the cytoplasm. Results of semi-quantitative RT-PCR showed that the initial abundance of mRNA encoding PssL protein was relatively lower when compared to the quantity of the previously identified PssT membrane protein. PssL might be a good candidate for Wzx-like protein that together with PssT (Wzy protein) could be responsible for Wzx/Wzy-like-dependent EPS polymerization and translocation in RtTA1.
除了pssT、pssN和pssP基因外，已鉴定出的pssL基因是另一个在豆科根瘤菌三叶草生物变种TA1（RtTA1）中编码参与多糖聚合和输出蛋白的基因。氨基酸序列相似性和假定的蛋白质二级结构将PssL蛋白置于具有假定翻转酶功能的Wzx（RfbX）转运蛋白中，该转运蛋白属于多糖特异性转运（PST）家族。使用一系列PssL-PhoA和PssL-LacZ翻译融合体检测了PssL膜蛋白的预测二级结构。结果支持了PssL是PST蛋白家族成员的假设，该家族包括具有12个跨膜区段且氨基和羧基末端位于细胞质中的转运蛋白。半定量RT-PCR结果表明，与先前鉴定的PssT膜蛋白的量相比，编码PssL蛋白的mRNA的初始丰度相对较低。PssL可能是类似Wzx蛋白的良好候选者，它与PssT（Wzy蛋白）一起可能负责RtTA1中Wzx/Wzy样依赖性胞外多糖的聚合和转运。
