Arginine repressor ArgR

In molecular biology, the arginine repressor (ArgR) is a repressor of prokaryotic arginine deiminase pathways.

Arginine repressor, C-terminal domain
c-terminal domain of escherichia coli arginine repressor/ l-arginine complex; pb derivative
Identifiers
SymbolArg_repressor_C
PfamPF02863
InterProIPR020899
SCOPe1aoy / SUPFAM
Arginine repressor, DNA binding domain
Identifiers
SymbolArg_repressor
PfamPF01316
SCOPe1aoy / SUPFAM

The arginine dihydrolase (AD) pathway is found in many prokaryotes and some eukaryotes, an example of the latter being Giardia lamblia (Giardia intestinalis).[1] The three-enzyme anaerobic pathway breaks down L-arginine to form 1 mol of ATP, carbon dioxide and ammonia. In some bacteria, the first enzyme, arginine deiminase, can account for up to 10% of total cell protein.[1]

Most prokaryotic arginine deiminase pathways are under the control of a repressor gene, termed ArgR.[2] This is a negative regulator, and will only release the arginine deiminase operon for expression in the presence of arginine.[3] The crystal structure of apo-ArgR from Bacillus stearothermophilus has been determined to 2.5A by means of X-ray crystallography.[4] The protein exists as a hexamer of identical subunits, and is shown to have six DNA-binding domains, clustered around a central oligomeric core when bound to arginine. It predominantly interacts with A.T residues in ARG boxes. This hexameric protein binds DNA at its N terminus to repress arginine biosynthesis or activate arginine catabolism. Some species have several ArgR paralogs. In a neighbour-joining tree, some of these paralogous sequences show long branches and differ significantly from the well-conserved C-terminal region.

References
  1. Brown DM, Upcroft JA, Edwards MR, Upcroft P (January 1998). "Anaerobic bacterial metabolism in the ancient eukaryote Giardia duodenalis". Int. J. Parasitol. 28 (1): 149–64. doi:10.1016/S0020-7519(97)00172-0. PMID 9504342.
  2. Lu CD, Houghton JE, Abdelal AT (May 1992). "Characterization of the arginine repressor from Salmonella typhimurium and its interactions with the carAB operator". J. Mol. Biol. 225 (1): 11–24. doi:10.1016/0022-2836(92)91022-H. PMID 1583685.
  3. Maghnouj A, de Sousa Cabral TF, Stalon V, Vander Wauven C (December 1998). "The arcABDC gene cluster, encoding the arginine deiminase pathway of Bacillus licheniformis, and its activation by the arginine repressor argR". J. Bacteriol. 180 (24): 6468–75. PMC 107747. PMID 9851988.
  4. Ni J, Sakanyan V, Charlier D, Glansdorff N, Van Duyne GD (May 1999). "Structure of the arginine repressor from Bacillus stearothermophilus". Nat. Struct. Biol. 6 (5): 427–32. doi:10.1038/8229. PMID 10331868.
This article incorporates text from the public domain Pfam and InterPro: IPR020899
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