PRIMARY SEQUENCE OF THE ESCHERICHIA-COLI FADL GENE ENCODING AN OUTER-MEMBRANE PROTEIN REQUIRED FOR LONG-CHAIN FATTY-ACID TRANSPORT
PRIMARY SEQUENCE OF THE ESCHERICHIA-COLI FADL GENE ENCODING AN OUTER-MEMBRANE PROTEIN REQUIRED FOR LONG-CHAIN FATTY-ACID TRANSPORT
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DOI：
10.1128/jb.173.2.435-442.1991
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发表时间：
1991-01-01
影响因子：
3.2
通讯作者：
BLACK, PN
中科院分区：
文献类型：
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作者：
BLACK, PN
大肠杆菌的fadL基因编码外膜蛋白（FadL），其在外源长链脂肪酸的摄取中起核心作用。 fadL基因的核苷酸序列揭示了1，344 bp的单个开放阅读框架，编码具有448个氨基酸残基和分子量为48，831的蛋白质。 通过引物延伸分析的转录起始点显示为翻译起始点上游95 bp。 在转录起始点上游-12和-37 bp处发现明显的-10和-35区域。 鉴定了具有连字符二分体对称性的三个区域（两个在转录起始和翻译起始之间，一个在-10和-35区域的上游），其可能在fadL的表达中起作用。 fadL基因的蛋白产物含有与其它大肠杆菌相似的信号序列和信号肽酶I切割位点。coli外膜蛋白。 成熟FadL蛋白的N-末端序列通过对从携带在T7 RNA聚合酶响应启动子控制下的fadL的菌株的外膜纯化的蛋白进行自动氨基酸测序来确定。 该氨基酸序列Ala-Gly-Phe-Gln-Leu-Asn-Glu-Phe-Ser-Ser证实了前FadL上的信号肽酶I切割位点，并证实了从DNA序列预测的FadL的N-末端氨基酸序列。 成熟的FadL含有421个氨基酸残基，分子量为45，969。 从DNA序列推断的FadL的氨基酸组成表明，该蛋白含有大量的疏水氨基酸残基，缺乏半胱氨酰残基。 预测FadL内的疏水性氨基酸有助于蛋白质的至少五个区域具有总体疏水特性。 利用FadL的氨基酸序列在GenBank中搜索与其氨基酸序列同源的蛋白质。 这些数据表明，FadL和流感嗜血杆菌B型热修饰外膜蛋白P1在438个氨基酸残基上的保守性为60.5%，同源性为42.0%。
The fadL gene of Escherichia coli encodes an outer membrane protein (FadL) that plays a central role in the uptake of exogenous long-chain fatty acids. The nucleotide sequence of the fadL gene revealed a single open reading frame of 1,344 bp encoding a protein with 448 amino acid residues and a molecular weight of 48,831. The transcriptional start, analyzed by primer extension, was shown to be 95 bp upstream from the translational start. Apparent - 10 and - 35 regions were found at - 12 and - 37 bp upstream from the transcriptional start. Three regions with hyphenated dyad symmetry (two between the transcriptional start and the translational start and one upstream from the - 10 and -35 regions) were identified that may play a role in the expression of fadL. The protein product of the fadL gene contained a signal sequence and signal peptidase I clevage site similar to that defined for other E. coli outer membrane proteins. The N-terminal sequence of the mature FadL protein was determined by automated amino acid sequencing of protein purified from the outer membrane of a strain harboring fadL under the control of a T7 RNA polymerase-responsive promoter. This amino acid sequence, Ala-Gly-Phe-Gln-Leu-Asn-Glu-Phe-Ser-Ser, verified the signal peptidase I cleavage site on pre-FadL and confirmed the N-terminal amino acid sequence of FadL predicted from the DNA sequence. Mature FadL contained 421 amino acid residues, giving a molecular weight of 45,969. The amino acid composition of FadL deduced from the DNA sequence suggested that this protein contained an abundance of hydrophobic amino acid residues and lacked cysteinyl residues. The hydrophobic amino acids within FadL were predicted to contribute to at least five regions of the protein with an overall hydrophobic character. The amino acid sequence of FadL was used to search GenBank for other proteins with amino acid sequence homology. These data demonstrated that FadL and the heat-modifiable outer membrane protein P1 of Haemophilus influenzae type b were 60.5% conserved and 42.0% identical over 438 amino acid residues.