Molecular identification and characterization of an alginate-binding protein on the cell surface of Sphingomonas sp A1
Molecular identification and characterization of an alginate-binding protein on the cell surface of Sphingomonas sp A1
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DOI：
10.1016/j.bbrc.2004.07.184
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发表时间：
2004-09-24
影响因子：
3.1
通讯作者：
Murata, K
中科院分区：
文献类型：
--
作者：
He, JS;Nankai, H;Murata, K
鞘氨醇单胞菌A1（菌株A1）的细胞通过生物系统或“超级通道”将大分子藻酸盐直接掺入细胞质中，该生物系统或“超级通道”由细胞表面上的凹坑、周质中的藻酸盐结合蛋白和内膜中的ABC转运蛋白组成。凹坑的功能是作为细胞外藻酸盐的浓缩器。通过差异显示分析，发现分子量为20 kDa和pI为7.4的蛋白质（p8）在藻酸盐生长的细胞的外膜中诱导表达。在菌株A1的基因组中鉴定了编码p8的基因，并显示其与真养罗尔斯通氏菌的聚羟基链烷酸酯颗粒相关蛋白的基因相似。p8基因阻断剂在藻酸盐培养基中表现出明显的生长抑制作用。在大肠杆菌中构建了p8的过表达系统，并对蛋白进行了纯化和表征。表面等离子体共振生物传感器分析表明，p8是能够结合海藻酸最有效地在pH 4.0。上述结果表明，p8是能够结合藻酸盐的细胞表面蛋白，并且促进藻酸盐在菌株A1的细胞表面上的凹坑中的浓缩。(C)2004年爱思唯尔公司All rights reserved.
Cells of Sphingomonas sp. A1 (strain A1) directly incorporate a macromolecule, alginate, into cytoplasm through a biosystem, or "super-channel," consisting of a pit on the cell surface, alginate-binding proteins in periplasm, and an ABC transporter in the inner membrane. The pit functions as a concentrator for extracellular alginate. Through differential display analysis, a protein (p8) with a molecular mass of 20 kDa and a pI of 7.4 was found to be inducibly expressed in the outer membrane of alginate-grown cells. The gene coding for p8 was identified in the genome of strain A1 and shown to be similar to that for the polyhydroxyalkanoate granule-associated protein of Ralstonia eutropha. The disruptant of p8 gene showed significant growth retardation in the alginate medium. An overexpression system for p8 was constructed in Escherichia coli, and the protein was purified and characterized. Surface plasmon resonance biosensor analysis indicated that p8 is able to bind alginate most efficiently at pH 4.0. The above results indicate that p8 is a cell surface protein able to bind alginate and facilitates the concentration of alginate in the pit on the cell surface of strain A1. (C) 2004 Elsevier Inc. All rights reserved.