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Escherichia coli K-12 substr. MG1655 Reaction: 2.7.1.156

Superclasses: Reactions Classified By Conversion Type Simple Reactions Chemical Reactions
Reactions Classified By Substrate Small-Molecule Reactions

EC Number: 2.7.1.156

Enzymes and Genes:
cobinamide kinase Inferred by computational analysis : cobU

In Pathway: adenosylcobalamin salvage from cobinamide I

Note that this reaction equation differs from the official Enzyme Commission reaction equations for this EC number.

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Most BioCyc compounds have been protonated to a reference pH value of 7.3, and some reactions have been computationally balanced for hydrogen by adding free protons. Please see the PGDB Concepts Guide for more information.

Mass balance status: Balanced.

Enzyme Commission Primary Name: adenosylcobinamide kinase

Enzyme Commission Synonyms: CobU, adenosylcobinamide kinase/adenosylcobinamide-phosphate guanylyltransferase, AdoCbi kinase/AdoCbi-phosphate guanylyltransferase

Summary:
This reaction is part of cobalamin biosynthesis.

Enzyme Commission Summary:
In Salmonella typhimurium LT2, under anaerobic conditions, CobU (EC 2.7.7.62 and EC 2.7.1.156), CobT (EC 2.4.2.21), CobC (EC 3.1.3.73) and CobS (EC 2.7.8.26) catalyse reactions in the nucleotide loop assembly pathway, which convert adenosylcobinamide (AdoCbi) into adenosylcobalamin (AdoCbl). CobT and CobC are involved in 5,6-dimethylbenzimidazole activation whereby 5,6-dimethylbenzimidazole is converted to its riboside, α-ribazole. The second branch of the nucleotide loop assembly pathway is the cobinamide (Cbi) activation branch where AdoCbi or adenosylcobinamide-phosphate is converted to the activated intermediate AdoCbi-GDP by Cob U. The final step in adenosylcobalamin biosynthesis is the condensation of AdoCbi-GDP with α-ribazole, which is catalysed by EC 2.7.8.26, adenosylcobinamide-GDP ribazoletransferase (CobS), to yield adenosylcobalamin. CobU is a bifunctional enzyme that has both kinase (EC 2.7.1.156) and guanylyltransferase (EC 2.7.7.62, adenosylcobinamide-phosphate guanylyltransferase) activities. However, both activities are not required at all times. The kinase activity has been proposed to function only when S. typhimurium is assimilating cobinamide whereas the guanylyltransferase activity is required for both assimilation of exogenous cobinamide and for de novo synthesis of adenosylcobalamin [Thomas00a].

Citations: [OToole95, Thompson98a, Thompson99b, Warren02]

Gene-Reaction Schematic: ?

Relationship Links: BRENDA:EC:2.7.1.156 , ENZYME:EC:2.7.1.156 , IUBMB-ExplorEnz:EC:2.7.1.156


References

OToole95: O'Toole GA, Escalante-Semerena JC (1995). "Purification and characterization of the bifunctional CobU enzyme of Salmonella typhimurium LT2. Evidence for a CobU-GMP intermediate." J Biol Chem 270(40);23560-9. PMID: 7559521

Thomas00a: Thomas MG, Thompson TB, Rayment I, Escalante-Semerena JC (2000). "Analysis of the adenosylcobinamide kinase/adenosylcobinamide-phosphate guanylyltransferase (CobU) enzyme of Salmonella typhimurium LT2. Identification of residue His-46 as the site of guanylylation." J Biol Chem 275(36);27576-86. PMID: 10869342

Thompson98a: Thompson TB, Thomas MG, Escalante-Semerena JC, Rayment I (1998). "Three-dimensional structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase from Salmonella typhimurium determined to 2.3 A resolution,." Biochemistry 37(21);7686-95. PMID: 9601028

Thompson99b: Thompson TB, Thomas MG, Escalante-Semerena JC, Rayment I (1999). "Three-dimensional structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase (CobU) complexed with GMP: evidence for a substrate-induced transferase active site." Biochemistry 38(40);12995-3005. PMID: 10529169

Warren02: Warren MJ, Raux E, Schubert HL, Escalante-Semerena JC (2002). "The biosynthesis of adenosylcobalamin (vitamin B12)." Nat Prod Rep 19(4);390-412. PMID: 12195810


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
Page generated by SRI International Pathway Tools version 18.5 on Sun Dec 21, 2014, biocyc14.