TY - JOUR T1 - Molecular basis for metabolite channeling in a ring opening enzyme of the phenylacetate degradation pathway. JF - Nat Commun Y1 - 2019 A1 - Sathyanarayanan, Nitish A1 - Cannone, Giuseppe A1 - Gakhar, Lokesh A1 - Katagihallimath, Nainesh A1 - Sowdhamini, Ramanathan A1 - Ramaswamy, Subramanian A1 - Vinothkumar, Kutti R AB -

Substrate channeling is a mechanism for the internal transfer of hydrophobic, unstable or toxic intermediates from the active site of one enzyme to another. Such transfer has previously been described to be mediated by a hydrophobic tunnel, the use of electrostatic highways or pivoting and by conformational changes. The enzyme PaaZ is used by many bacteria to degrade environmental pollutants. PaaZ is a bifunctional enzyme that catalyzes the ring opening of oxepin-CoA and converts it to 3-oxo-5,6-dehydrosuberyl-CoA. Here we report the structures of PaaZ determined by electron cryomicroscopy with and without bound ligands. The structures reveal that three domain-swapped dimers of the enzyme form a trilobed structure. A combination of small-angle X-ray scattering (SAXS), computational studies, mutagenesis and microbial growth experiments suggests that the key intermediate is transferred from one active site to the other by a mechanism of electrostatic pivoting of the CoA moiety, mediated by a set of conserved positively charged residues.

VL - 10 IS - 1 ER -