Raina R, Bageshwar U K, Das H K
Genetic Engineering Unit, Jawaharlal Nehru University, New Delhi, India.
Mol Gen Genet. 1993 Mar;237(3):400-6. doi: 10.1007/BF00279444.
The nucleotide sequence of the Azotobacter vinelandii nifL-like gene (Av-nifL) was determined. The 1.9 kb sequence shows an open reading frame (ORF) of 1577 bp which encodes a polypeptide of 519 amino acids, with a calculated molecular weight of 57,793. Av-nifL has about 50% homology with the Klebsiella pneumoniae nifL gene (Kp-nifL) at the nucleotide level and a little more than 52% homology at the amino acid level. The N-terminal regions show more homology than the C-terminal regions. As is the case in K. pneumoniae, Av-nifL is located just upstream of the A. vinelandii nifA gene (Av-nifA) and both genes constitute an operon. The expression of Av-nifL, however, seems to be independent of NtrA and NtrC. Furthermore, Av-nifL expression is not autogenously regulated by NifA, unlike the case in K. pneumoniae. The expression of an Av-nifL::lacZ fusion in A. vinelandii is inhibited by novobiocin and coumermycin A, which are inhibitors of DNA gyrase.
测定了棕色固氮菌中类nifL基因（Av-nifL）的核苷酸序列。1.9kb的序列显示出一个1577bp的开放阅读框（ORF），其编码一个由519个氨基酸组成的多肽，计算分子量为57793。Av-nifL在核苷酸水平上与肺炎克雷伯氏菌nifL基因（Kp-nifL）有大约50%的同源性，在氨基酸水平上同源性略高于52%。N端区域比C端区域显示出更多的同源性。与肺炎克雷伯氏菌的情况一样，Av-nifL位于棕色固氮菌nifA基因（Av-nifA）的上游，这两个基因构成一个操纵子。然而，Av-nifL的表达似乎独立于NtrA和NtrC。此外，与肺炎克雷伯氏菌不同，Av-nifL的表达不受NifA的自体调节。在棕色固氮菌中，Av-nifL::lacZ融合蛋白的表达受到新霉素和香豆霉素A的抑制，这两种物质是DNA回旋酶的抑制剂。
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