CalE6 from Micromonospora echinospora is a (pyridoxal 5′ phosphate) PLP-dependent methionine γ-lyase involved in the biosynthesis of calicheamicins. We report the crystal structure of a CalE6 2-(N-morpholino)ethanesulfonic acidcomplex showing ligand-induced rotation of Tyr100, which stacks with PLP, resembling the corresponding tyrosine rotation of true catalytic intermediates of CalE6 homologs. Elastic network modeling and crystallographic ensemble refinement reveal mobility of the N-terminal loop, which involves both tetrameric assembly and PLP binding. Modeling and comparative structuralanalysis of PLP-dependent enzymes involved in Cys/Met metabolism shine light on the functional implications of the intrinsic dynamic properties of CalE6 in catalysis and holoenzyme maturation.
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This work was supported by the National Institutes of Health Grant Nos. CA84374 (J.S.T.), U01GM098248 (G.N.P.), and GM094585 (A.J.) and the National Center for Advancing Translational Sciences (UL1TR000117).
Cao, Hongnan; Tan, Kemin; Wang, Fengbin; Bigelow, Lance; Yennamalli, Ragothaman M.; Jedrzejczak, Robert; Babnigg, Gyorgy; Bingman, Craig A.; Joachimiak, Andrzej; Kharel, Madan K.; Singh, Shanteri; Thorson, Jon S.; and Phillips, George N. Jr., "Structural Dynamics of a Methionine γ-lyase for Calicheamicin Biosynthesis: Rotation of the Conserved Tyrosine Stacking with Pyridoxal Phosphate" (2016). Pharmaceutical Sciences Faculty Publications. 71.