4FAZ

Kinetic and structural characterization of the 4-oxalocrotonate tautomerase isozymes from Methylibium petroleiphilum

Summary for 4FAZ

• Entry DOI: 10.2210/pdb4faz/pdb
• Related: 4FDX
• Descriptor: 4-oxalocrotonate isomerase protein, SULFATE ION (3 entities in total)
• Functional Keywords: alpha/beta fold, tautomerase, isomerase
• Biological source: Methylibium petroleiphilum
• Total number of polymer chains: 3
• Total formula weight: 20837.99

Authors

Terrell, C.R.,Hoffman, D.W.,Whitman, C.P. (deposition date: 2012-05-22, release date: 2013-06-05, Last modification date: 2023-09-13)

Primary citation

Terrell, C.R.,Burks, E.A.,Whitman, C.P.,Hoffman, D.W.
Structural and kinetic characterization of two 4-oxalocrotonate tautomerases in Methylibium petroleiphilum strain PM1.
Arch.Biochem.Biophys., 537:113-124, 2013

PubMed Abstract: Methylibium petroleiphilum strain PM1 uses various petroleum products including the fuel additive methyl tert-butyl ether and straight chain and aromatic hydrocarbons as sole carbon and energy sources. It has two operons, dmpI and dmpII, that code for the enzymes in a pair of parallel meta-fission pathways. In order to understand the roles of the pathways, the 4-oxalocrotonate tautomerase (4-OT) isozyme from each pathway was characterized. Tautomerase I and tautomerase II have the lowest pairwise sequence identity (35%) among the isozyme pairs in the parallel pathways, and could offer insight into substrate preferences and pathway functions. The kinetic parameters of tautomerase I and tautomerase II were determined using 2-hydroxymuconate and 5-(methyl)-2-hydroxymuconate. Both tautomerase I and tautomerase II process the substrates, but with different efficiencies. Crystal structures were determined for both tautomerase I and tautomerase II, at 1.57 and 1.64Å resolution, respectively. The backbones of tautomerase I and tautomerase II are highly similar, but have distinct active site environments. The results, in combination with those for other structurally and kinetically characterized 4-OT isozymes, suggest that tautomerase I catalyzes the tautomerization of both 2-hydroxymuconate and alkyl derivatives, whereas tautomerase II might specialize in other aromatic hydrocarbon metabolites.

PubMed: 23831510
DOI: 10.1016/j.abb.2013.06.016

Experimental method

X-RAY DIFFRACTION (1.57 Å)