Schlensog V, Lutz S, Böck A
Lehrstuhl für Mikrobiologie der Universität München, Germany.
J Biol Chem. 1994 Jul 29;269(30):19590-6.
FHLA is the transcriptional activator for the expression of the genes coding for components of the formate hydrogenlyase system of Escherichia coli. The cloned fhlA gene was overexpressed under selected growth conditions, and a purification protocol for the FHLA protein was developed. Purified FHLA in the native state is a homotetramer. It binds to the upstream regulatory sequences of the fdhF gene and of the intergenic region between the divergently transcribed hyc and hyp operons. An additional binding site of FHLA located between the hycA and hycB genes was identified. While binding to the hypA-hycA intergenic region is responsible for activation of expression of the hyc operon, the newly identified site is required for the activation of the sigma 54-dependent promoter located upstream of the hyp operon. Formate seems to have no effect on the DNA-binding properties of FHLA. The binding sites of FHLA were characterized by DNase I footprinting; sequence motifs putatively involved in the interaction with FHLA are described.
FHLA是大肠杆菌甲酸氢裂解酶系统组分编码基因表达的转录激活因子。克隆的fhlA基因在特定生长条件下过表达，并开发了一种FHLA蛋白的纯化方案。天然状态下纯化的FHLA是一种同四聚体。它与fdhF基因以及反向转录的hyc和hyp操纵子之间基因间区域的上游调控序列结合。在hycA和hycB基因之间鉴定出了FHLA的另一个结合位点。虽然与hypA-hycA基因间区域的结合负责激活hyc操纵子的表达，但新鉴定的位点是激活hyp操纵子上游的σ54依赖性启动子所必需的。甲酸似乎对FHLA的DNA结合特性没有影响。通过DNase I足迹法对FHLA的结合位点进行了表征；描述了可能参与与FHLA相互作用的序列基序。
