6OGM

Crystal structure of apo unFused 4-OT

Summary for 6OGM

• Entry DOI: 10.2210/pdb6ogm/pdb
• Related: 6BLM
• Descriptor: 4-oxalocrotonate tautomerase, GLYCEROL, ... (4 entities in total)
• Functional Keywords: hydrolase
• Biological source: Burkholderia lata (strain ATCC 17760 / DSM 23089 / LMG 22485 / NCIMB 9086 / R18194 / 383); More
• Total number of polymer chains: 12
• Total formula weight: 79559.20

Authors

Medellin, B.P.,Whitman, C.P.,Zhang, Y.J. (deposition date: 2019-04-03, release date: 2020-02-26, Last modification date: 2023-10-25)

Primary citation

Baas, B.J.,Medellin, B.P.,LeVieux, J.A.,de Ruijter, M.,Zhang, Y.J.,Brown, S.D.,Akiva, E.,Babbitt, P.C.,Whitman, C.P.
Structural, Kinetic, and Mechanistic Analysis of an Asymmetric 4-Oxalocrotonate Tautomerase Trimer.
Biochemistry, 58:2617-2627, 2019

PubMed Abstract: A 4-oxalocrotonate tautomerase (4-OT) trimer has been isolated from Burkholderia lata, and a kinetic, mechanistic, and structural analysis has been performed. The enzyme is the third described oligomer state for 4-OT along with a homo- and heterohexamer. The 4-OT trimer is part of a small subset of sequences (133 sequences) within the 4-OT subgroup of the tautomerase superfamily (TSF). The TSF has two distinct features: members are composed of a single β-α-β unit (homo- and heterohexamer) or two consecutively joined β-α-β units (trimer) and generally have a catalytic amino-terminal proline. The enzyme, designated as fused 4-OT, functions as a 4-OT where the active site groups (Pro-1, Arg-39, Arg-76, Phe-115, Arg-127) mirror those in the canonical 4-OT from Pseudomonas putida mt-2. Inactivation by 2-oxo-3-pentynoate suggests that Pro-1 of fused 4-OT has a low p K enabling the prolyl nitrogen to function as a general base. A remarkable feature of the fused 4-OT is the absence of P3 rotational symmetry in the structure (1.5 Å resolution). The asymmetric arrangement of the trimer is not due to the fusion of the two β-α-β building blocks because an engineered "unfused" variant that breaks the covalent bond between the two units (to generate a heterohexamer) assumes the same asymmetric oligomerization state. It remains unknown how the different active site configurations contribute to the observed overall activities and whether the asymmetry has a biological purpose or role in the evolution of TSF members.

PubMed: 31074977
DOI: 10.1021/acs.biochem.9b00303

Experimental method

X-RAY DIFFRACTION (1.865 Å)