%0 Journal Article %J Nat Commun %D 2019 %T Molecular basis for metabolite channeling in a ring opening enzyme of the phenylacetate degradation pathway. %A Sathyanarayanan, Nitish %A Cannone, Giuseppe %A Gakhar, Lokesh %A Katagihallimath, Nainesh %A Sowdhamini, Ramanathan %A Ramaswamy, Subramanian %A Vinothkumar, Kutti R %X

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.

%B Nat Commun %V 10 %P 4127 %8 2019 Sep 11 %G eng %N 1 %R 10.1038/s41467-019-11931-1