3 OVERLAPPING LCT GENES INVOLVED IN L-LACTATE UTILIZATION BY ESCHERICHIA-COLI
3 OVERLAPPING LCT GENES INVOLVED IN L-LACTATE UTILIZATION BY ESCHERICHIA-COLI
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DOI：
10.1128/jb.175.20.6671-6678.1993
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发表时间：
1993-10-01
影响因子：
3.2
通讯作者：
LIN, ECC
中科院分区：
文献类型：
--
作者：
DONG, JM;TAYLOR, JS;LIN, ECC
在大肠杆菌中，染色体图谱上最小80处的lct位点与在L-乳酸盐上生长和合成底物诱导的黄素连接脱氢酶的能力相关。与glpD编码的需氧甘油-3-磷酸脱氢酶类似，需氧生活提高了诱导的酶活性水平。这两种控制都是由双组分信号转导系统ArcB/ArcA介导的，尽管L-乳酸脱氢酶对控制的敏感性要显著得多。这项研究揭示，lct基因座包含三个重叠的基因，顺时针顺序lctD（编码黄素单核苷酸依赖性脱氢酶），lctR（编码一个假定的调节器），和lctP（编码一个通透酶）的染色体图谱。这些基因。然而，是逆时针方向转录的。乳酸脱氢酶与好氧甘油-3-磷酸脱氢酶的氨基酸序列没有同源性。一个PHI（lctD-lac）突变体是由L-乳酸诱导，但不是D-乳酸。虽然突变体失去了在L-乳酸盐上生长的能力，但已知依赖于不同酶的D-乳酸盐的生长仍然正常。
In Escherichia coli, the lct locus at min 80 on the chromosome map is associated with ability to grow on L-lactate and to synthesize a substrate-inducible flavin-linked dehydrogenase. Similar to that of the glpD-encoded aerobic glycerol-3-phosphate dehydrogenase, the level of induced enzyme activity is elevated by aerobiosis. Both of these controls are mediated by the two-component signal transduction system ArcB/ArcA, although sensitivity to the control is much more striking for L-lactate dehydrogenase. This study disclosed that the lct locus contained three overlapping genes in the clockwise order of lctD (encoding a flavin mononucleotide-dependent dehydrogenase), lctR (encoding a putative regulator), and lctP (encoding a permease) on the chromosomal map. These genes. however, are transcribed in the counterclockwise direction. No homology in amino acid sequence was found between aerobic glycerol-3-phosphate dehydrogenase and L-lactate dehydrogenase. A PHI(lctD-lac) mutant was inducible by L-lactate but not D-lactate. Although the mutant lost the ability to grow on L-lactate, growth on D-lactate, known to depend on a different enzyme, remained normal.