Structural highlights
Function
[OTC1_ECOLI] Reversibly catalyzes the transfer of the carbamoyl group from carbamoyl phosphate (CP) to the N(epsilon) atom of ornithine (ORN) to produce L-citrulline, which is a substrate for argininosuccinate synthetase, the enzyme involved in the final step in arginine biosynthesis.[1] [2]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The crystal structure is reported at 1.8 A resolution of Escherichia coli ornithine transcarbamoylase in complex with the active derivative of phaseolotoxin from Pseudomonas syringae pv. phaseolicola, N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine. Electron density reveals that the complex is not a covalent adduct as previously thought. Kinetic data confirm that N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine exhibits reversible inhibition with a half-life in the order of approximately 22 h and a dissociation constant of K(D) = 1.6 x 10(-12) m at 37 degrees C and pH 8.0. Observed hydrogen bonding about the chiral tetrahedral phosphorus of the inhibitor is consistent only with the presence of the R enantiomer. A strong interaction is also observed between Arg(57) Nepsilon and the P-N-S bridging nitrogen indicating that imino tautomers of N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine are present in the bound state. An imino tautomer of N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine is structurally analogous to the proposed reaction transition state. Hence, we propose that N(delta)-(N'-sulfodiaminophosphinyl)-l-ornithine, with its three unique N-P bonds, represents a true transition state analogue for ornithine transcarbamoylases, consistent with the tight binding kinetics observed.
Mechanism of inactivation of ornithine transcarbamoylase by Ndelta -(N'-Sulfodiaminophosphinyl)-L-ornithine, a true transition state analogue? Crystal structure and implications for catalytic mechanism.,Langley DB, Templeton MD, Fields BA, Mitchell RE, Collyer CA J Biol Chem. 2000 Jun 30;275(26):20012-9. PMID:10747936[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Kuo LC, Miller AW, Lee S, Kozuma C. Site-directed mutagenesis of Escherichia coli ornithine transcarbamoylase: role of arginine-57 in substrate binding and catalysis. Biochemistry. 1988 Nov 29;27(24):8823-32. PMID:3072022
- ↑ Legrain C, Stalon V, Glansdorff N. Escherichia coli ornithine carbamolytransferase isoenzymes: evolutionary significance and the isolation of lambdaargF and lambdaargI transducing bacteriophages. J Bacteriol. 1976 Oct;128(1):35-8. PMID:789338
- ↑ Langley DB, Templeton MD, Fields BA, Mitchell RE, Collyer CA. Mechanism of inactivation of ornithine transcarbamoylase by Ndelta -(N'-Sulfodiaminophosphinyl)-L-ornithine, a true transition state analogue? Crystal structure and implications for catalytic mechanism. J Biol Chem. 2000 Jun 30;275(26):20012-9. PMID:10747936 doi:10.1074/jbc.M000585200
