KEGG   ENZYME: 5.4.99.13Help
Entry
EC 5.4.99.13                Enzyme                                 

Name
isobutyryl-CoA mutase;
isobutyryl coenzyme A mutase;
butyryl-CoA:isobutyryl-CoA mutase;
icmA (gene name);
icmB (gene name);
icmF (gene name)
Class
Isomerases;
Intramolecular transferases;
Transferring other groups
BRITE hierarchy
Sysname
2-methylpropanoyl-CoA CoA-carbonylmutase
Reaction(IUBMB)
2-methylpropanoyl-CoA = butanoyl-CoA [RN:R01181]
Reaction(KEGG)
Substrate
2-methylpropanoyl-CoA [CPD:C00630]
Product
butanoyl-CoA [CPD:C00136]
Comment
This bacterial enzyme utilizes 5'-deoxyadenosylcobalamin as a cofactor. Following substrate binding, the enzyme catalyses the homolytic cleavage of the cobalt-carbon bond of AdoCbl, yielding cob(II)alamin and a 5'-deoxyadenosyl radical, which initiates the the carbon skeleton rearrangement reaction by hydrogen atom abstraction from the substrate. At the end of each catalytic cycle the 5'-deoxyadenosyl radical and cob(II)alamin recombine, regenerating the resting form of the cofactor. The enzyme is prone to inactivation resulting from occassional loss of the 5'-deoxyadenosyl molecule. Inactivated enzymes are repaired by the action of EC 2.5.1.17, cob(I)yrinic acid a,c-diamide adenosyltransferase, and a G-protein chaperone, which restore cob(II)alamin (which is first reduced to cob(I)alamin by an unidentified reductase) to 5'-deoxyadenosylcobalamin and load it back on the mutase. Some mutases are fused with their G-protein chaperone. These enzyme can also catalyse the interconversion of isovaleryl-CoA with pivalyl-CoA.
History
EC 5.4.99.13 created 1992, revised 2017
Reference
1
  Authors
Brendelberger, G., Retey, J., Ashworth, D.M., Reynolds, K., Willenbrock, F. and Robinson, J.A.
  Title
The enzymic interconversion of isobutyryl and N-butyrylcarba(dethia)-coenzyme-A - a coenzyme-B12-dependent carbon skeleton rearrangement.
  Journal
Angew. Chem. Int. Ed. Engl. 27 (1988) 1089-1091.
Reference
2  [PMID:10531377]
  Authors
Ratnatilleke A, Vrijbloed JW, Robinson JA.
  Title
Cloning and sequencing of the coenzyme B(12)-binding domain of isobutyryl-CoA mutase from Streptomyces cinnamonensis, reconstitution of mutase activity, and characterization of the recombinant enzyme produced in Escherichia coli.
  Journal
J. Biol. Chem. 274 (1999) 31679-85.
Reference
3  [PMID:19864421]
  Authors
Cracan V, Padovani D, Banerjee R
  Title
IcmF is a fusion between the radical B12 enzyme isobutyryl-CoA mutase and its G-protein chaperone.
  Journal
J. Biol. Chem. 285 (2010) 655-66.
Reference
4  [PMID:22167181]
  Authors
Cracan V, Banerjee R
  Title
Novel coenzyme B12-dependent interconversion of isovaleryl-CoA and pivalyl-CoA.
  Journal
J. Biol. Chem. 287 (2012) 3723-32.
Reference
5  [PMID:26318610]
  Authors
Jost M, Born DA, Cracan V, Banerjee R, Drennan CL
  Title
Structural Basis for Substrate Specificity in Adenosylcobalamin-dependent Isobutyryl-CoA Mutase and Related Acyl-CoA Mutases.
  Journal
J. Biol. Chem. 290 (2015) 26882-98.
Reference
6  [PMID:28130442]
  Authors
Li Z, Kitanishi K, Twahir UT, Cracan V, Chapman D, Warncke K, Banerjee R
  Title
Cofactor Editing by the G-protein Metallochaperone Domain Regulates the Radical B12 Enzyme IcmF.
  Journal
J. Biol. Chem. 292 (2017) 3977-3987.
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
116405-23-3

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