5TIG

CRYSTAL STRUCTURE OF 4-OXALOCROTONATE TAUTOMERASE INACTIVATED BY BrHPD

Summary for 5TIG

• Entry DOI: 10.2210/pdb5tig/pdb
• Descriptor: 2-hydroxymuconate tautomerase, (3E)-5-hydroxy-2-oxopent-3-enoic acid (3 entities in total)
• Functional Keywords: isomerase, isomerase-isomerase inhibitor complex, isomerase/isomerase inhibitor
• Biological source: Pseudomonas putida
• Total number of polymer chains: 30
• Total formula weight: 205826.03

Authors

Zhang, Y.,Li, W.,Stack, T. (deposition date: 2016-10-02, release date: 2018-02-21, Last modification date: 2024-10-30)

Primary citation

Stack, T.M.M.,Li, W.,Johnson, W.H.,Zhang, Y.J.,Whitman, C.P.
Inactivation of 4-Oxalocrotonate Tautomerase by 5-Halo-2-hydroxy-2,4-pentadienoates.
Biochemistry, 57:1012-1021, 2018

PubMed Abstract: 5-Halo-2-hydroxy-2,4-pentadienoates (5-halo-HPDs) are reportedly generated in the bacterial catabolism of halogenated aromatic hydrocarbons by the meta-fission pathway. The 5-halo-HPDs, where the halogen can be bromide, chloride, or fluoride, result in the irreversible inactivation of 4-oxalocrotonate tautomerase (4-OT), which precedes the enzyme that generates them. The loss of activity is due to the covalent modification of the nucleophilic amino-terminal proline. Mass spectral and crystallographic analysis of the modified enzymes indicates that inactivation of 4-OT by 5-chloro- and 5-bromo-2-hydroxy-2,4-pentadienoate follows a mechanism different from that for the inactivation of 4-OT by 5-fluoro-2-hydroxy-2,4-pentadienoate. The 5-chloro and 5-bromo derivatives undergo 4-OT-catalyzed tautomerization to their respective α,β-unsaturated ketones followed by attack at C5 (by the prolyl nitrogen) with concomitant loss of the halide. For the 5-fluoro species, the presence of a small amount of the α,β-unsaturated ketone could result in a Michael addition of the prolyl nitrogen to C4 followed by protonation at C3. The fluoride is not eliminated. These observations suggest that the inactivation of 4-OT by a downstream metabolite could hamper the efficacy of the pathway, which is the first time that such a bottleneck has been reported for the meta-fission pathway.

PubMed: 29303557
DOI: 10.1021/acs.biochem.7b00899

Experimental method

X-RAY DIFFRACTION (2.7 Å)