Cloning and nucleotide sequence of the Bacillus subtilis hom gene coding for homoserine dehydrogenase. Structural and evolutionary relationships with Escherichia coli aspartokinases-homoserine dehydrogenases I and II.
Cloning and nucleotide sequence of the Bacillus subtilis hom gene coding for homoserine dehydrogenase. Structural and evolutionary relationships with Escherichia coli aspartokinases-homoserine dehydrogenases I and II.
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DOI：
10.1016/s0021-9258(18)68087-1
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发表时间：
1988-10
期刊：
影响因子：
--
通讯作者：
C. Parsot;G. Cohen
中科院分区：
文献类型：
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作者：
C. Parsot;G. Cohen
已克隆了编码高丝氨酸脱氢酶（L-高丝氨酸：NADP+氧化还原酶，EC 1.1.1.3）的枯草芽孢杆菌hom基因，并测定了其核苷酸序列。B。在大肠杆菌中表达的枯草杆菌酶对苏氨酸的抑制敏感，并允许缺乏高丝氨酸脱氢酶I和II的菌株互补。核苷酸序列分析表明，hom终止密码子与thrC（苏氨酸合成酶）的起始密码子重叠，表明这些基因以及位于thrC下游的thrB（高丝氨酸激酶）属于同一个转录单位。推导的B的氨基酸序列。枯草杆菌高丝氨酸脱氢酶与大肠杆菌的C-末端部分具有广泛的相似性。大肠杆菌激酶-高丝氨酸激酶I和II之间的相似性;这种相似性开始于大肠杆菌激酶-高丝氨酸激酶I和II之间的相似性的确切点。coli或B.枯草芽孢杆菌激酶和E.大肠杆菌激酶-高丝氨酸激酶停止。这些数据表明，E.大肠杆菌双功能多肽可能是由祖先的葡激酶和高丝氨酸脱氢酶直接融合而成。B。枯草杆菌高丝氨酸脱氢酶具有约100个残基的C-末端延伸（相对于E.大肠杆菌酶），其可能参与酶活性的调节。
The Bacillus subtilis hom gene, encoding homoserine dehydrogenase (L-homoserine:NADP+ oxidoreductase, EC 1.1.1.3) has been cloned and its nucleotide sequence determined. The B. subtilis enzyme expressed in Escherichia coli is sensitive by inhibition by threonine and allows complementation of a strain lacking homoserine dehydrogenases I and II. Nucleotide sequence analysis indicates that the hom stop codon overlaps the start codon of thrC (threonine synthase) suggesting that these genes, as well as thrB (homoserine kinase) located downstream from thrC, belong to the same transcription unit. The deduced amino acid sequence of the B. subtilis homoserine dehydrogenase shows extensive similarity with the C-terminal part of E. coli aspartokinases-homoserine dehydrogenases I and II; this similarity starts at the exact point where the similarity between E. coli or B. subtilis aspartokinases and E. coli aspartokinases-homoserine dehydrogenases stops. These data suggest that the E. coli bifunctional polypeptide could have resulted from the direct fusion of ancestral aspartokinase and homoserine dehydrogenase. The B. subtilis homoserine dehydrogenase has a C-terminal extension of about 100 residues (relative to the E. coli enzymes) that could be involved in the regulation of the enzyme activity.