Wu L F, Tomich J M, Saier M H
Department of Biology, University of California, San Diego, La Jolla 92093.
J Mol Biol. 1990 Jun 20;213(4):687-703. doi: 10.1016/S0022-2836(05)80256-6.
The gene order of the fructose (fru) operon and nucleotide sequence of the first gene (fruB(HI) of Rhodobacter capsulatus are reported, analyzed and compared with homologous genes from other bacteria, and the gene products are identified. Included within the region reported is a gene encoding a multiphosphoryl transfer protein (MTP) of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). MTP consists of three moieties: a fructose-specific enzyme III (IIIfru)-like N-terminal moiety (residues 1 to 143) followed by an FPr(HPr)-like moiety (residues 157 to 245) and an enzyme I-like moiety (residues 273 to 827). The enzyme III-like moiety closely resembles the N-terminal 143 residues of the IIIfru-FPR fusion protein from Salmonella typhimurium (40.6% identity throughout its length) and the C-terminal 145 residues of the mannitol-specific enzyme II (IImtl) (37.8% identity throughout its length with the IIImtl moiety of IImtl). The FPr-like domain of MTP resembles the S. typhimurium FPr (42.4% identity) and the Escherichia coli or S. typhimurium HPr (38.8% identity). The enzyme I-like moiety resembles the E. coli enzyme I (38.9% identity). Predicted phosphorylation sites within the three functional units of MTP (His62 in the IIIfru-like moiety; His171 in the FPr-like moiety and His457 in the enzyme I-like moiety) were identified on the basis of sequence comparisons with the homologous proteins from enteric bacteria. The three functional domains of MTP are joined by two flexible "linkage" regions, rich in alanine, glycine and proline, which show 47% sequence identity with each other. They also exhibit a high degree of sequence identity with the linkage region of the mannose-specific enzyme III (IIIman) of the E. coli PTS as well as several other proteins of bacterial, eukaryotic and viral origin. At the RNA level, these linker regions formed hairpin structures with high (90%) G + C content. Analyses of the IIIfru-FPr fusion protein of S. typhimurium revealed that between the IIIfru and FPr moieties of this protein is a stretch of 142 amino acids that do not show homology to known PTS proteins. This region and the adjacent FPr-like region contain a sequence of 110 residues exhibiting 59% similarity to the receiver consensus motif defined by Kofoid and Parkinson. Because the Salmonella IIIfru-FPr fusion protein has been implicated in transcriptional regulation, this region of the Salmonella protein may prove to have regulatory significance.(ABSTRACT TRUNCATED AT 400 WORDS)
报道、分析了荚膜红细菌果糖（fru）操纵子的基因顺序及首个基因（fruB(HI)）的核苷酸序列，并与其他细菌的同源基因进行了比较，还鉴定了基因产物。所报道区域内包含一个编码磷酸烯醇丙酮酸：糖磷酸转移酶系统（PTS）的多磷酸转移蛋白（MTP）的基因。MTP由三个部分组成：一个果糖特异性酶III（IIIfru）样的N端部分（第1至143位氨基酸残基），接着是一个FPr（HPr）样部分（第157至245位氨基酸残基）和一个酶I样部分（第273至827位氨基酸残基）。酶III样部分与鼠伤寒沙门氏菌IIIfru - FPR融合蛋白的N端143个氨基酸残基非常相似（全长40.6%的同一性），与甘露醇特异性酶II（IImtl）的C端145个氨基酸残基相似（与IImtl的IIImtl部分全长有37.8%的同一性）。MTP的FPr样结构域与鼠伤寒沙门氏菌FPr相似（42.4%的同一性），与大肠杆菌或鼠伤寒沙门氏菌HPr相似（38.8%的同一性）。酶I样部分与大肠杆菌酶I相似（38.9%的同一性）。基于与肠道细菌同源蛋白的序列比较，确定了MTP三个功能单元内的预测磷酸化位点（IIIfru样部分的His62；FPr样部分的His171和酶I样部分的His457）。MTP的三个功能结构域由两个富含丙氨酸、甘氨酸和脯氨酸的柔性“连接”区域相连，这两个区域彼此有47%的序列同一性。它们与大肠杆菌PTS的甘露糖特异性酶III（IIIman）的连接区域以及细菌、真核生物和病毒来源的其他几种蛋白质也有高度的序列同一性。在RNA水平上，这些连接区域形成了G + C含量高（90%）的发夹结构。对鼠伤寒沙门氏菌IIIfru - FPr融合蛋白的分析表明，该蛋白的IIIfru和FPr部分之间有一段142个氨基酸的序列，与已知的PTS蛋白没有同源性。该区域和相邻的FPr样区域包含一段110个残基的序列，与Kofoid和Parkinson定义的受体共有基序有59%的相似性。由于鼠伤寒沙门氏菌IIIfru - FPr融合蛋白与转录调控有关，该沙门氏菌蛋白的这一区域可能具有调控意义。（摘要截短至400字）
