Roles for GcvA-binding sites 3 and 2 and the Lrp-binding region in gcvT:: lacZ expression in Escherichia coli

• Published in: Microbiology (Society for General Microbiology) Vol. 144; no. 10; pp. 2865 - 2872
• Main Authors: Stauffer, Lorraine T, Stauffer, George V
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.10.1998; Society for General Microbiology
• Subjects: Aminomethyltransferase; Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Base Sequence; Biological and medical sciences; Dimerization; DNA, Bacterial - chemistry; DNA, Bacterial - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Genetics; Hydroxymethyl and Formyl Transferases - biosynthesis; Hydroxymethyl and Formyl Transferases - genetics; Lac Operon; Low Density Lipoprotein Receptor-Related Protein-1; Lysogeny; Microbiology; Models, Genetic; Nucleic Acid Conformation; Operon - genetics; Receptors, Immunologic - genetics; Receptors, Immunologic - metabolism; Recombinant Fusion Proteins - biosynthesis; Repressor Proteins - genetics; Repressor Proteins - metabolism; Response Elements - genetics; Sequence Deletion; Trans-Activators - genetics; Trans-Activators - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Escherichia coli; Activation; Metabolism; Gene expression; Glycine; Structure function relationship; Mechanism; Regulation(control); Molecular bending; Aminoacid; Bacteria; Cleavage; Enterobacteriaceae
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-144-10-2865

Department of Iowa, Iowa City, IA 52242, USA University Of Iowa City, IA 52242, USA 1 Author for correspondence: George V. Stauffer. Tel: + 1 319 33.5 7791. Fax: + 1 319 33.5 9006. e-mail: george-stauffer@uiowa.edu ABSTRACT SUMMARY: GcvA and Lrp are both necessary for activation of the gcv operon. The upstream GcvA-binding sites 3 and 2 were separated from the Lrplbinding region and the rest of the gcv control region. Moving these sites by 1 or 2 helical turns of DNA further from the gcv promoter reduces, but does not eliminate, either GcvA-mediated activation or repression of a gcvT:: lac2 gene fusion. However, moving these sites by 1-5 or 2.5 helical turns of DNA results inm a GcvA-mediated super-repression of the operon. This repression is dependent on Lrp and is partially dependent on GcvR. Lrp bound to the gcv control region induces a bend in the DNA. Based on these results, a model for gcw regulation is presented in which Lrp plays a primarily structural role, by bending the DNA and GcvA functions as the activator protein. Keywords: glycine cleavage, gcvT:: lacz, GcvA, Lrp, DNA bending