Download MendeleyCrystallographic Snapshots of the Dunathan and Quinonoid Intermediates provide Insights into the Reaction Mechanism of Group II Decarboxylases.
Gayathri, S.C., Manoj, N.(2020) J Mol Biol 432: 166692-166692
- PubMed: 33122004
- DOI: https://doi.org/10.1016/j.jmb.2020.10.026
- Primary Citation of Related Structures:
6M4Y - PubMed Abstract:
PLP-dependent enzymes catalyze a plethora of chemical reactions affecting diverse physiological functions. Here we report the structural determinants of the reaction mechanism in a Group II PLP-dependent decarboxylase by assigning two early intermediates. The in-crystallo complexes of the PLP bound form, and the Dunathan and quinonoid intermediates, allowed direct observation of the active site interactions. The structures reveal that a subtle rearrangement of a conserved Arg residue in concert with a water-mediated interaction with the carboxylate of the Dunathan intermediate, appears to directly stabilize the alignment and facilitate the release of CO 2 to yield the quinonoid. Modeling indicates that the conformational change of a dynamic catalytic loop to a closed form controls a conserved network of hydrogen bond interactions between catalytic residues to protonate the quinonoid. Our results provide a structural framework to elucidate mechanistic roles of residues that govern reaction specificity and catalysis in PLP-dependent decarboxylation.
Organizational Affiliation:
Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
