Menaquinone (vitamin K2) biosynthesis: nucleotide sequence and expression of the menB gene from Escherichia coli.
Menaquinone (vitamin K2) biosynthesis: nucleotide sequence and expression of the menB gene from Escherichia coli.
复制标题
甲萘醌（维生素 K2）生物合成：大肠杆菌 menB 基因的核苷酸序列和表达。
DOI：
10.1128/jb.174.15.5057-5062.1992
复制
发表时间：
1992
影响因子：
3.2
通讯作者：
Hudspeth,ME
中科院分区：
文献类型：
--
作者：
Sharma,V;Suvarna,K;Meganathan,R;Hudspeth,ME
在大肠杆菌中，电子载体甲基萘醌（维生素K2）的生物合成涉及至少七种已确定的酶。其中一种是萘酸合成酶，它通过催化邻琥珀酰苯甲酰辅酶A转化为1,4-二羟基-2-萘酸而形成双环体系。这种酶的基因先前已被确定为b型脑膜炎杆菌。通过遗传和生化测试，来自大肠杆菌男性位点的1.349 kb DNA片段与menB突变体互补。该片段包含一个285个密码子的开放阅读框（ORF）。含有ORF的氨基区或羧基区缺失的重组质粒不能对突变体进行补体。ORF之前有核糖体结合位点和sigma 70启动子的一致序列。足以在体内和体外补充menB突变体的menB转录可以从鉴定的推定启动子启动，并且在构建中，menB的表达可以独立于lac启动子的可读转录。然而，含有menB的多拷贝质粒不能产生预期的酶活性水平。
In Escherichia coli, the biosynthesis of the electron carrier menaquinone (vitamin K2) involves at least seven identified enzymes. One of these, naphthoate synthase, forms the bicyclic ring system by catalyzing the conversion of o-succinylbenzoyl-coenzyme A to 1,4-dihydroxy-2-naphthoic acid. The gene for this enzyme has been previously identified as menB. By genetic and biochemical tests, a 1.349-kb DNA fragment from the E. coli men locus complements menB mutants. This fragment contains a single 285-codon open reading frame (ORF). Recombinant plasmids containing deletions of either the amino or the carboxy region of the ORF fail to complement the mutants. The ORF is preceded by consensus sequences for a ribosomal binding site and a sigma 70 promoter. menB transcription sufficient to complement the menB mutant in vivo and in vitro can be initiated from the identified putative promoter, and that in the constructs, menB expression, can be made independent of read-through transcription from the lac promoter. However, multicopy plasmids containing menB fail to generate the expected levels of enzymatic activity.