Literature summary for 6.3.5.5 extracted from

Delannay, S.; Charlier, D.; Tricot, C.; Villeret, V.; Pierard, A.; Stalon, V.
Serine 948 and threonine 1042 are crucial residues for allosteric regulation of Escherichia coli carbamoylphosphate synthetase and illustrate coupling effects of activation and inhibition pathways (1999), J. Mol. Biol., 286, 1217-1228.

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Activating Compound

Activating Compound	Comment	Organism	Structure
IMP	-	Escherichia coli
L-ornithine	-	Escherichia coli

Cloned(Commentary)

Cloned (Comment)	Organism
cloning of car B wild-type and mutant enzymes	Escherichia coli

Protein Variants

Protein Variants	Comment	Organism
A182V	reduced apparent affinity for HCO3-, sensitivity toward UMP is unchanched in comparison to wild-type enzyme	Escherichia coli
A182V/S948F	mutant is insensitive towards pyrimidine and purine nucleosides, activation by ornithine, although the affinity for this ligand is fivefold reduced in comparison to wild-type enzyme	Escherichia coli
G824D	strongly reduced affinity for ornithine in comparison to wild-type enzyme	Escherichia coli
P165S	reduced apparent affinity for HCO3-, sensitivity toward UMP is increased in comparison to wild-type enzyme	Escherichia coli
P170L	reduced apparent affinity for HCO3-, sensitivity toward UMP is increased in comparison to wild-type enzyme	Escherichia coli
P360L	UMP still inhibits the activity of the mutant enzyme, 30fold reduced affinity for ornithine and 20fold reduced affinity for IMP in comparison to wild-type enzyme	Escherichia coli
S743N	minor modification of kinetic parameters in comparison to wild-type enzyme	Escherichia coli
S743N/G824D	strongly reduced affinity for ornithine in comparison to wild-type enzyme	Escherichia coli
S948F	mutant enzyme is unsensitive to UMP and IMP, but is still activated by ornithine, although to a reduced extent	Escherichia coli
T1042I	greatly reduced activation by ornithine, the affinities for both UMP and IMP are reduced in comparison to wild-type enzyme in comparison to wild-type enzyme	Escherichia coli
T1042I	mutation reduces activation by ornithine, the mutated enzyme is still sensitive to UMP and IMP	Escherichia coli
T800F	reduced affinity for ornithine, increased sensitivity for UMP in comparison to wild-type enzyme	Escherichia coli

Inhibitors

Inhibitors	Comment	Organism	Structure
UMP	-	Escherichia coli

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
0.12	-	L-glutamine	pH 7.5, 37°C, value of wild-type enzyme in comparison to values of mutant enzymes	Escherichia coli
1.2	-	HCO3-	pH 7.5, 37°C, value of wild-type enzyme in comparison to values of mutant enzymes	Escherichia coli

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
2 ATP + L-Gln + HCO3-	Escherichia coli	enzyme is a key enzyme in the pyrimidine nucleotide and arginine biosynthetic pathways	2 ADP + phosphate + L-Glu + carbamoyl phosphate	-	?

Organism

Organism	UniProt	Comment	Textmining
Escherichia coli	-	K-12	-

Purification (Commentary)

Purification (Comment)	Organism
recombinant wild-type and mutant enzymes	Escherichia coli

Reaction

Reaction	Comment	Organism	Reaction ID
2 ATP + L-glutamine + hydrogencarbonate + H2O = 2 ADP + phosphate + L-glutamate + carbamoyl phosphate	two residues, Ser948 and Thr1042, appear crucial for allosteric regulation of enzyme	Escherichia coli	a

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
2 ATP + L-Gln + HCO3-	-	Escherichia coli	2 ADP + phosphate + L-Glu + carbamoyl phosphate	-	?
2 ATP + L-Gln + HCO3-	enzyme is a key enzyme in the pyrimidine nucleotide and arginine biosynthetic pathways	Escherichia coli	2 ADP + phosphate + L-Glu + carbamoyl phosphate	-	?

Ki Value [mM]

Ki Value [mM]	Ki Value maximum [mM]	Inhibitor	Comment	Organism	Structure
0.005	-	UMP	pH 7.5, 37°C, value of wild-type enzyme in comparison to values of mutant enzymes	Escherichia coli

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Release 2023.1 (January 2023)