Glycine binds the transcriptional accessory protein GcvR to disrupt a GcvA/GcvR interaction and allow GcvA-mediated activation of the Escherichia coli gcvTHP operon

• Published in: Microbiology (Society for General Microbiology) Vol. 148; no. 7; pp. 2203 - 2214
• Main Authors: Heil, Gary, Stauffer, Lorraine T, Stauffer, George V
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.07.2002; Society for General Microbiology
• Subjects: Amino Acid Oxidoreductases - genetics; Amino Acid Oxidoreductases - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Base Sequence; Binding Sites; Biological and medical sciences; Carrier Proteins - genetics; Carrier Proteins - 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; GcvA protein; GcvR protein; Gene Expression Regulation, Bacterial; Genetics; Glycine - metabolism; LysR protein; Microbiology; Molecular Sequence Data; Multienzyme Complexes - genetics; Multienzyme Complexes - metabolism; Operon; Repressor Proteins - genetics; Repressor Proteins - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Transferases - genetics; Transferases - metabolism; Regulation(control); Nucleotide sequence; Operon; Aminoacid; Escherichia coli; Bacteria; Gene expression; Glycine; Enterobacteriaceae
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-148-7-2203

Department of Microbiology, The University of Iowa, Iowa City, IA 52242, USA 1 Author for correspondence: George V. Stauffer. Tel: +1 319 335 7791. Fax: +1 319 335 9006. e-mail: george-stauffer{at}uiowa.edu The Escherichia coli gcvTHP operon is under control of the LysR-type transcriptional regulator GcvA. GcvA activates the operon in the presence of glycine and represses the operon in its absence. Repression by GcvA is dependent on a second regulatory protein, GcvR. Generally, LysR-type transcriptional regulators bind to specific small co-effector molecules which results in either their altered affinity for specific binding sites on the DNA or altered ability to bend the DNA, resulting in either activation or repression of their respective operons. This study shows that glycine, the co-activator for the gcv operon, does not alter either GcvA’s ability to bind DNA nor its ability to bend DNA. Rather, glycine binds to GcvR, disrupting a GcvA/GcvR interaction required for repression and allowing GcvA activation of the gcvTHP operon. Amino acid changes in GcvR that reduce glycine binding result in a loss of glycine-mediated activation in vivo. Keywords: gcvTHP , GcvA, GcvR, glycine, repression Abbreviations: AP, ampicillin; C1, one-carbon; co-ppt, co-precipitation; gcv , gcvTHP operon; GCV, glycine cleavage; GMS, gel mobility shift; LTTR, LysR-type transcriptional regulator; RNAP, RNA polymerase; TPEG, phenylethyl-ß-D-thiogalactoside