Byrne C R, Monroe R S, Ward K A, Kredich N M
Division of Animal Production, Commonwealth Scientific and Industrial Research Organisation, Blacktown, New South Wales, Australia.
J Bacteriol. 1988 Jul;170(7):3150-7. doi: 10.1128/jb.170.7.3150-3157.1988.
Nucleotide sequences of the cysK regions of Salmonella typhimurium and Escherichia coli have been determined. A total of 3,812 and 2,595 nucleotides were sequenced from S. typhimurium and E. coli, respectively. Open reading frames of 323 codons were found in both species and were identified as those of cysK by comparison of deduced amino acid sequences with amino- and carboxyl-terminal amino acid analyses of the S. typhimurium cysK gene product O-acetylserine (thiol)-lyase A. The two cysK DNA sequences were 85% identical, and the deduced amino acid sequences were 96% identical. The major transcription initiation sites for cysK were found to be virtually identical in the two organisms, by using primer extension and S1 nuclease protection techniques. The -35 region corresponding to the major transcription start site was TTCCCC in S. typhimurium and TTCCGC in E. coli. The deviation of these sequences from the consensus sequence TTGACA may reflect the fact that cysK is subject to positive control and requires the cysB regulatory protein for expression. Sequences downstream of cysK were found to include ptsH and a portion of ptsI, thus establishing the exact relationship of cysK with these two genes. A 290-codon open reading frame, which may represent the cysZ gene, was identified upstream of cysK.
已测定了鼠伤寒沙门氏菌和大肠杆菌cysK区域的核苷酸序列。分别从鼠伤寒沙门氏菌和大肠杆菌中测序了3812个和2595个核苷酸。在这两个物种中均发现了323个密码子的开放阅读框，通过将推导的氨基酸序列与鼠伤寒沙门氏菌cysK基因产物O - 乙酰丝氨酸（硫醇）- 裂解酶A的氨基末端和羧基末端氨基酸分析进行比较，将其鉴定为cysK的开放阅读框。这两个cysK DNA序列的同一性为85%，推导的氨基酸序列的同一性为96%。通过使用引物延伸和S1核酸酶保护技术，发现cysK在这两种生物中的主要转录起始位点实际上是相同的。鼠伤寒沙门氏菌中与主要转录起始位点相对应的 - 35区域是TTCCCC，大肠杆菌中是TTCCGC。这些序列与共有序列TTGACA的偏差可能反映了cysK受正调控且表达需要cysB调节蛋白这一事实。发现cysK下游的序列包括ptsH和ptsI的一部分，从而确定了cysK与这两个基因的确切关系。在cysK上游鉴定出一个可能代表cysZ基因的290个密码子的开放阅读框。
