Lactate Utilization Is Regulated by the FadR-Type Regulator LldR in Pseudomonas aeruginosa
Lactate Utilization Is Regulated by the FadR-Type Regulator LldR in Pseudomonas aeruginosa
复制标题
铜绿假单胞菌中的乳酸利用受 FadR 型调节因子 LldR 的调节
DOI：
10.1128/jb.06579-11
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发表时间：
2012-05-01
影响因子：
3.2
通讯作者：
Xu, Ping
中科院分区：
文献类型：
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作者：
Gao, Chao;Hu, Chunhui;Xu, Ping
在假单胞菌中，乳酸盐的两种对映体都能协同诱导NAD非依赖性l-乳酸脱氢酶（l-iLDH）和NAD非依赖性d-乳酸脱氢酶（d-iLDH）的活性。对不同假单胞菌菌株的基因组序列的检查揭示了lldPDE操纵子包含3个基因，lldP（编码乳酸通透酶）、lldD（编码I-iLDH）和lldE（编码d-iLDH）。铜绿假单胞菌菌株XMG中lldP、lldD和lldE的共转录起始于位于lldP ATG起始密码子上游138 bp的碱基C。lldPDE操纵子位于lldR（编码FadR型调节子，LldR）附近。凝胶迁移率变动分析显示，纯化的His-标记的LldR结合到lldP的上游区域。发现组成型表达d-iLDH和l-iLDH的XMG突变株在lldR中含有突变，其导致LldR蛋白中的Ile 23-丝氨酸取代。突变的蛋白质LldRM失去了其DNA结合活性。一个基序与一个连字符的二分体对称性（TGGTCTTACCA）被确定为必需的LldR的结合，通过使用定点诱变的上游区域的lldP。l-乳酸和d-乳酸干扰LldR的DNA结合活性。因此，当在l-乳酸或d-乳酸存在下诱导操纵子时，表达l-iLDH和d-iLDH。
ABSTRACT NAD-independent l-lactate dehydrogenase (l-iLDH) and NAD-independent d-lactate dehydrogenase (d-iLDH) activities are induced coordinately by either enantiomer of lactate in Pseudomonas strains. Inspection of the genomic sequences of different Pseudomonas strains revealed that the lldPDE operon comprises 3 genes, lldP (encoding a lactate permease), lldD (encoding an l-iLDH), and lldE (encoding a d-iLDH). Cotranscription of lldP, lldD, and lldE in Pseudomonas aeruginosa strain XMG starts with the base, C, that is located 138 bp upstream of the lldP ATG start codon. The lldPDE operon is located adjacent to lldR (encoding an FadR-type regulator, LldR). The gel mobility shift assays revealed that the purified His-tagged LldR binds to the upstream region of lldP. An XMG mutant strain that constitutively expresses d-iLDH and l-iLDH was found to contain a mutation in lldR that leads to an Ile23-to-serine substitution in the LldR protein. The mutated protein, LldRM, lost its DNA-binding activity. A motif with a hyphenated dyad symmetry (TGGTCTTACCA) was identified as essential for the binding of LldR to the upstream region of lldP by using site-directed mutagenesis. l-Lactate and d-lactate interfered with the DNA-binding activity of LldR. Thus, l-iLDH and d-iLDH were expressed when the operon was induced in the presence of l-lactate or d-lactate.