6xa3

Publication Abstract from PubMed

Biocatalysis offers an expanding and powerful strategy to construct and diversify complex molecules by C horizontal line H bond functionalization. Due to their high selectivity, enzymes have become an essential tool for C horizontal line H bond functionalization and offer complementary reactivity to small-molecule catalysts. Hemoproteins, particularly cytochromes P450, have proven effective for selective oxidation of unactivated C horizontal line H bonds. Previously, we reported the in vitro characterization of an oxidative tailoring cascade in which TamI, a multifunctional P450 functions co-dependently with the TamL flavoprotein to catalyze regio- and stereoselective hydroxylations and epoxidation to yield tirandamycin A and tirandamycin B. TamI follows a defined order including 1) C10 hydroxylation, 2) C11/C12 epoxidation, and 3) C18 hydroxylation. Here we present a structural, biochemical, and computational investigation of TamI to understand the molecular basis of its substrate binding, diverse reactivity, and specific reaction sequence. The crystal structure of TamI in complex with tirandamycin C together with molecular dynamics simulations and targeted mutagenesis suggest that hydrophobic interactions with the polyene chain of its natural substrate are critical for molecular recognition. QM calculations and molecular dynamics simulations of TamI with variant substrates provided detailed information on the molecular basis of sequential reactivity, and pattern of regio- and stereo-selectivity in catalyzing the three-step oxidative cascade.

Molecular Basis of Iterative C horizontal line H Oxidation by TamI, a Multifunctional P450 monooxygenase from the Tirandamycin Biosynthetic Pathway.,Newmister SA, Srivastava KR, Espinoza RV, Haatveit KC, Khatri Y, Martini RM, Garcia-Borras M, Podust LM, Houk KN, Sherman DH ACS Catal. 2020 Nov 20;10(22):13445-13454. doi: 10.1021/acscatal.0c03248. Epub, 2020 Nov 4. PMID:33569241^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.