两个重叠的巴西固氮螺菌上游激活序列对nifH启动子活性具有不同影响。

The two overlapping Azospirillum brasilense upstream activator sequences have differential effects on nifH promoter activity.

作者信息

Passaglia L M, Schrank A, Schrank I S

机构信息

Departamento de Genética, Universidade Federal do Rio Grande do Sul, Brazil.

出版信息

Can J Microbiol. 1995 Sep;41(9):849-54. doi: 10.1139/m95-117.

DOI:10.1139/m95-117

PMID:7585362

Abstract

The Azospirillum brasilense nifH promoter is positively controlled by the NifA protein bound to the upstream activator sequences (UASs). Two overlapping UASs located at -191 and -182 were identified with the consensus TGT-N10-ACA motif. The role of the two UASs of Azospirillum brasilense nifH promoter was examined by introducing base substitutions in the NifA binding sites. Both the promoter down phenotype of a mutation in UAS2 and increased activation when UAS1 was mutated reveal that the integrity of the UAS2 is required for the efficient activation of nifH promoter. This atypical NifA-binding site may represent a region interacting with two NifA dimers.

摘要

巴西固氮螺菌nifH启动子受与上游激活序列（UASs）结合的NifA蛋白正向调控。在-191和-182位置鉴定出两个重叠的UASs，其共有基序为TGT-N10-ACA。通过在NifA结合位点引入碱基替换，研究了巴西固氮螺菌nifH启动子两个UASs的作用。UAS2突变导致的启动子下调表型以及UAS1突变时激活增加，均表明UAS2的完整性是nifH启动子高效激活所必需的。这个非典型的NifA结合位点可能代表一个与两个NifA二聚体相互作用的区域。