SILENT AND FUNCTIONAL-CHANGES IN THE PERIPLASMIC MALTOSE-BINDING PROTEIN OF ESCHERICHIA-COLI-K12 .1. TRANSPORT OF MALTOSE
SILENT AND FUNCTIONAL-CHANGES IN THE PERIPLASMIC MALTOSE-BINDING PROTEIN OF ESCHERICHIA-COLI-K12 .1. TRANSPORT OF MALTOSE
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DOI：
10.1016/0022-2836(87)90243-9
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发表时间：
1987-04-20
影响因子：
5.6
通讯作者：
HOFNUNG, M
中科院分区：
文献类型：
--
作者：
DUPLAY, P;SZMELCMAN, S;HOFNUNG, M
malE基因编码周质麦芽糖结合蛋白（MBP）。19个突变，仍然允许合成稳定的MBP产生的随机插入的BamHI八核苷酸到malE和6个额外的突变体基因之间的体外重组。测定序列变化;在大多数情况下，接头插入伴随着小的缺失（平均30个碱基对）。研究了突变体MBP的输出、在麦芽糖和麦芽糊精上的生长、麦芽糖的转运和结合以及麦芽糖诱导的荧光变化。在周质空间中发现了16个突变MBP（详细研究了21个突变MBP）：其中12个保留了对麦芽糖的高亲和力，10个保留了对麦芽糖生长的活性。结果表明，MBP的几个区域的稳定性，底物结合和输出。三个区域（残基207至220、297至303和364至370）可能涉及与MalF或MalG蛋白的相互作用。靠近C末端的区域对于麦芽糖结合是重要的。成熟蛋白质的两个区域（残基18至42和280至296）需要输出到周质或溶解于周质中。
The malE gene encodes the periplasmic maltose-binding protein (MBP). Nineteen mutations that still permit synthesis of stable MBP were generated by random insertion of a BamHI octanucleotide into malE and six additional mutations by in-vitro recombinations between mutant genes. The sequence changes were determined; in most cases the linker insertion is accompanied by a small deletion (30 base-pairs on average). The mutant MBP were studied for export, growth on maltose and maltodextrins, maltose transport and binding, and maltose-induced fluorescence changes. Sixteen mutant MBP (out of 21 studied in detail) were found in the periplasmic space: 12 of them retained a high affinity for maltose, and 10 activity for growth on maltose. The results show that several regions of MBP are dispensable for stability, substrate binding and export. Three regions (residues 207 to 220, 297 to 303 and 364 to 370) may be involved in interactions with the MalF or MalG proteins. A region near the C-terminal end is important for maltose binding. Two regions of the mature protein (residues 18 to 42 and 280 to 296) are required for export to, or solubility in, the periplasm.