8V8M

Switchgrass Chalcone Synthase

Summary for 8V8M

• Entry DOI: 10.2210/pdb8v8m/pdb
• Related: 8V8L 8V8N 8V8O 8V8P
• Descriptor: Chalcone synthase, COENZYME A, NARINGENIN, ... (4 entities in total)
• Functional Keywords: chalcone synthase, flavonoids, chalcones, transferase
• Biological source: Panicum virgatum (switchgrass)
• Total number of polymer chains: 4
• Total formula weight: 175474.12

Authors

Lewis, J.A.,Kang, C. (deposition date: 2023-12-05, release date: 2024-05-29, Last modification date: 2024-10-30)

Primary citation

Lewis, J.A.,Jacobo, E.P.,Palmer, N.,Vermerris, W.,Sattler, S.E.,Brozik, J.A.,Sarath, G.,Kang, C.
Structural and Interactional Analysis of the Flavonoid Pathway Proteins: Chalcone Synthase, Chalcone Isomerase and Chalcone Isomerase-like Protein.
Int J Mol Sci, 25:-, 2024

PubMed Abstract: Chalcone synthase (CHS) and chalcone isomerase (CHI) catalyze the first two committed steps of the flavonoid pathway that plays a pivotal role in the growth and reproduction of land plants, including UV protection, pigmentation, symbiotic nitrogen fixation, and pathogen resistance. Based on the obtained X-ray crystal structures of CHS, CHI, and chalcone isomerase-like protein (CHIL) from the same monocotyledon, , along with the results of the steady-state kinetics, spectroscopic/thermodynamic analyses, intermolecular interactions, and their effect on each catalytic step are proposed. In addition, PvCHI's unique activity for both naringenin chalcone and isoliquiritigenin was analyzed, and the observed hierarchical activity for those type-I and -II substrates was explained with the intrinsic characteristics of the enzyme and two substrates. The structure of PvCHS complexed with naringenin supports uncompetitive inhibition. PvCHS displays intrinsic catalytic promiscuity, evident from the formation of -coumaroyltriacetic acid lactone (CTAL) in addition to naringenin chalcone. In the presence of PvCHIL, conversion of -coumaroyl-CoA to naringenin through PvCHS and PvCHI displayed ~400-fold increased with reduced formation of CTAL by 70%. Supporting this model, molecular docking, ITC (Isothermal Titration Calorimetry), and FRET (Fluorescence Resonance Energy Transfer) indicated that both PvCHI and PvCHIL interact with PvCHS in a non-competitive manner, indicating the plausible allosteric effect of naringenin on CHS. Significantly, the presence of naringenin increased the affinity between PvCHS and PvCHIL, whereas naringenin chalcone decreased the affinity, indicating a plausible feedback mechanism to minimize spontaneous incorrect stereoisomers. These are the first findings from a three-body system from the same species, indicating the importance of the macromolecular assembly of CHS-CHI-CHIL in determining the amount and type of flavonoids produced in plant cells.

PubMed: 38891840
DOI: 10.3390/ijms25115651

Experimental method

X-RAY DIFFRACTION (1.82 Å)