Lamblin A F, Fuchs J A
Department of Biochemistry, University of Minnesota, St. Paul 55108.
J Bacteriol. 1994 Nov;176(21):6613-22. doi: 10.1128/jb.176.21.6613-6622.1994.
The cynTSX operon enables Escherichia coli K-12 to degrade and use cyanate as a sole nitrogen source. The promoter of this operon is positively regulated by cyanate and the CynR protein. CynR, a member of the LysR family of regulatory proteins, binds specifically to a 136-bp DNA fragment containing both the cynR and the cynTSX promoters. In this study, we report the results of DNase I digestion studies showing that CynR protects a 60-bp region on the cynR coding strand and a 56-bp sequence on the cynTSX coding strand. CynR binding was not affected by cyanate or its structural homolog azide, a gratuitous inducer of the operon. However, CynR-induced bending of two different DNA fragments was detected. The amount of bending was decreased by cyanate.
cynTSX操纵子使大肠杆菌K-12能够降解并利用氰酸盐作为唯一氮源。该操纵子的启动子受氰酸盐和CynR蛋白的正向调控。CynR是调控蛋白LysR家族的成员，它特异性结合一个包含cynR和cynTSX启动子的136bp DNA片段。在本研究中，我们报告了DNA酶I消化研究的结果，结果表明CynR保护cynR编码链上一个60bp的区域和cynTSX编码链上一个56bp的序列。CynR的结合不受氰酸盐或其结构类似物叠氮化物（该操纵子的 gratuitous诱导物）的影响。然而，检测到CynR诱导的两个不同DNA片段的弯曲。氰酸盐可减少弯曲量。
