Transcriptional activation of the Escherichia coli adaptive response gene aidB is mediated by binding of methylated Ada protein. Evidence for a new consensus sequence for Ada-binding sites
UMass Chan Affiliations
Department of Molecular Genetics and MicrobiologyDocument Type
Journal ArticlePublication Date
1995-04-07Keywords
Adaptation, PhysiologicalBacterial Proteins
Base Sequence
Binding Sites
*Consensus Sequence
Deoxyribonuclease I
Escherichia coli
*Escherichia coli Proteins
Gene Expression Regulation
Methylation
Molecular Sequence Data
O(6)-Methylguanine-DNA Methyltransferase
Protein Binding
Regulatory Sequences, Nucleic Acid
*Trans-Activation (Genetics)
Transcription Factors
Transcription, Genetic
Life Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
The Escherichia coli aidB gene is part of the adaptive response to DNA methylation damage. Genes belonging to the adaptive response are positively regulated by the ada gene; the Ada protein acts as a transcriptional activator when methylated in one of its cysteine residues at position 69. Through DNaseI protection assays, we show that methylated Ada (meAda) is able to bind a DNA sequence between 40 and 60 base pairs upstream of the aidB transcriptional startpoint. Binding of meAda is necessary to activate transcription of the adaptive response genes; accordingly, in vitro transcription of aidB is dependent on the presence of meAda. Unmethylated Ada protein shows no protection against DNaseI digestion in the aidB promoter region nor does it promote aidB in vitro transcription. The aidB Ada-binding site shows only weak homology to the proposed consensus sequences for Ada-binding sites in E. coli (AAANNAA and AAAGCGCA) but shares a higher degree of similarity with the Ada-binding regions from other bacterial species, such as Salmonella typhimurium and Bacillus subtilis. Based on the comparison of five different Ada-dependent promoter regions, we suggest that a possible recognition sequence for meAda might be AATnnnnnnG-CAA. Higher concentrations of Ada are required for the binding of aidB than for the ada promoter, suggesting lower affinity of the protein for the aidB Ada-binding site. Common features in the Ada-binding regions of ada and aidB are a high A/T content, the presence of an inverted repeat structure, and their position relative to the transcriptional start site. We propose that these elements, in addition to the proposed recognition sequence, are important for binding of the Ada protein.Source
J Biol Chem. 1995 Apr 7;270(14):8285-9.
DOI
10.1074/jbc.270.14.8285Permanent Link to this Item
http://hdl.handle.net/20.500.14038/42466PubMed ID
7713936Related Resources
ae974a485f413a2113503eed53cd6c53
10.1074/jbc.270.14.8285
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