1BJP

CRYSTAL STRUCTURE OF 4-OXALOCROTONATE TAUTOMERASE INACTIVATED BY 2-OXO-3-PENTYNOATE AT 2.4 ANGSTROMS RESOLUTION

Summary for 1BJP

• Entry DOI: 10.2210/pdb1bjp/pdb
• Descriptor: 4-OXALOCROTONATE TAUTOMERASE, 2-OXO-3-PENTENOIC ACID (3 entities in total)
• Functional Keywords: tautomerase, isomerase, microbial biodegradation
• Biological source: Pseudomonas putida
• Total number of polymer chains: 5
• Total formula weight: 34679.69

Authors

Taylor, A.B.,Czerwinski, R.M.,Johnson Junior, W.H.,Whitman, C.P.,Hackert, M.L. (deposition date: 1998-06-26, release date: 1998-12-02, Last modification date: 2024-10-23)

Primary citation

Taylor, A.B.,Czerwinski, R.M.,Johnson Jr., W.H.,Whitman, C.P.,Hackert, M.L.
Crystal structure of 4-oxalocrotonate tautomerase inactivated by 2-oxo-3-pentynoate at 2.4 A resolution: analysis and implications for the mechanism of inactivation and catalysis.
Biochemistry, 37:14692-14700, 1998

PubMed Abstract: The crystal structure of 4-oxalocrotonate tautomerase (4-OT) inactivated by the active site-directed irreversible inhibitor 2-oxo-3-pentynoate (2-OP) has been determined to 2.4 A resolution. The structure of the enzyme covalently modified at Pro-1 by the resulting 2-oxo-3-pentenoate adduct is nearly superimposable on that of the free enzyme and confirms that the active site is located in a hydrophobic region surrounding Pro-1. Both structures can be described as a trimer of dimers where each dimer consists of a four-stranded beta-sheet with two antiparallel alpha-helices on one side. Examination of the structure also reveals noncovalent interactions between the adduct and two residues in the active site. The epsilon and eta nitrogens of the guanidinium side chain of Arg-39" from a neighboring dimer interact respectively with the C-2 carbonyl oxygen and one C-1 carboxylate oxygen of the adduct while the side chain of Arg-61' from the same dimer as the modified Pro-1 interacts with the C-1 carboxylate group in a bidentate fashion. An additional interaction to the 2-oxo group of the adduct is provided by one of the two ordered water molecules within the active site region. These interactions coupled with the observation that 2-oxo-3-butynoate is a more potent irreversible inhibitor of 4-oxalocrotonate tautomerase than is 2-OP suggest that Arg-39" and the ordered water molecule polarize the carbonyl group of 2-OP which facilitates a Michael reaction between Pro-1 and the acetylene compound. On the basis of the crystal structure, a mechanism for the enzyme-catalyzed reaction is proposed.

PubMed: 9778344
DOI: 10.1021/bi981607j

Experimental method

X-RAY DIFFRACTION (2.4 Å)