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Figure 1
Overall crystal structure of SeEN. The enzyme is likely to adopt an octameric quaternary structure comprising four heart-shaped dimers or pseudo-dimers (shaded yellow). In the resting state, SeEN shows one Ca2+ ion (Ca1 site) coordinated to Asp246, Glu287 and Asp314. The segment 43-PSGASTGTF-51 is conformationally flexible and closes on the active-site cleft upon sequential entrance of the substrate and a second Ca2+ ion (Ca2 site). In this way, the backbone carbonyl of Ala46 becomes a ligand of Ca2. Proton extraction from 2PGA is assumed to occur from behind by Lys339 acting as a strong base, whereas hydration of PEP is believed to take place from the opposite side by a water molecule hydrogen-bonded to Glu209 and Glu168.

Journal logoSTRUCTURAL BIOLOGY
COMMUNICATIONS
ISSN: 2053-230X
Volume 78| Part 4| April 2022| Pages 177-184
https://doi.org/10.1107/S2053230X22003612
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