Disease relevance of gcvH

• Characterization of the Escherichia coli gcv operon [1].

High impact information on gcvH

• In this study, the cyclic AMP (cAMP) receptor protein (CRP) is shown to be involved in positive regulation of the gcv operon [2].
• Furthermore, the deletion of bcp from the chromosome had no effect on gcv-lacZ expression [3].
• The GcvA protein is a LysR family regulatory protein necessary for both activation and repression of the Escherichia coli glycine cleavage enzyme operon (gcv) and negative regulation of gcvA [4].
• Three separate GcvA binding sites in gcv were identified by DNase I footprint analysis: a 29-bp region extending from positions -271 to -242, a 28-bp region extending from -242 to -214, and a 35-bp region covering positions -69 to -34 relative to the transcription initiation site [4].
• RNA slot blot analyses indicated that induction of gcv by glycine, and PurR-mediated repression of gcv occur at the level of transcription [1].

Chemical compound and disease context of gcvH

• Cloning and nucleotide sequence of the gcv operon encoding the Escherichia coli glycine-cleavage system [5].

Biological context of gcvH

• The translation start site was determined by N-terminal amino acid sequence analysis of a gcvH-lacZ encoded fusion protein [6].
• However, bacteria harboring the plasmid that contained the gcv operon without the promoter region and the 5' terminal portion of gcvT failed to overexpress any of the three components [5].
• A new mutation in Escherichia coli, designated gcvA1, that results in noninducible expression of both gcv and a gcvT-lacZ gene fusion was isolated [7].
• The results suggest that the gcv regulatory region is complex, with numerous cis-acting sites that are required for normal gcv expression [8].

Associations of gcvH with chemical compounds

• However, overexpression of gcvR re-established purine-mediated repression of the gcvT::lacZ fusion, supporting the model for gcv regulation that suggests the need for a relatively constant GcvA to GcvR ratio for appropriate regulation of gcv expression in response to glycine and purine availability [9].
• The presence of acetate and succinate in the growth medium of a strain wild type for lpd and gcv resulted in a 50% reduction in inducible GCV enzyme activity [10].
• However, when these sites were moved by approximately 1.5 and 2.5 helical turns of DNA away from the gcv promoter, there was a complete loss of both glycine-mediated activation and inosine-mediated repression of the gcvT::IacZ fusion [11].
• The new mutations, designated gcv, were mapped between the serA and lys genes at 62.5 min on the S. typhimurium chromosome [12].
• Tolerance appears to involve increased metabolism of glycine (higher expression of gcv genes) and increased production of betaine (higher expression of betIBA and betT encoding betaine synthesis from choline and choline uptake, respectively) [13].

Regulatory relationships of gcvH

• GcvA binds to three sites in the gcv control region and to one site in the gcvA control region; each of these binding sites contains the conserved 5 bp DNA sequence 5'-CTAAT-3'. This report describes the role this DNA sequence plays in autoregulation and expression of gcvA [9].

Other interactions of gcvH

• These genes are named gcvT, gcvH and gcvP, respectively [5].
• The gcvT gene is transcribed and translated in the same direction as the gcvH gene [14].
• However, when a gcv mutation, which causes glycine to accumulate within the cell, was introduced into the cycA strain, there was increased induction of the gcvT::lacZ fusion, but induction was less than that observed in a gcv cycA+ strain [15].

References