Structural origins of the selectivity of the trifunctional oxygenase clavaminic acid synthase.
Clavaminate synthase (CAS), a remarkable Fe(II)/2-oxoglutarate oxygenase, catalyzes three separate oxidative reactions in the biosynthesis of clavulanic acid, a clinically used inhibitor of serine beta-lactamases. The first CAS-catalyzed step (hydroxylation) is separated from the latter two (oxidative cyclization/desaturation) by the action of an amidinohydrolase. Here, we describe crystal structures of CAS in complex with Fe(II), 2-oxoglutarate (2OG) and substrates (N-alpha-acetyl-L-arginine and proclavaminic acid). They reveal how CAS catalyzes formation of the clavam nucleus, via a process unprecedented in synthetic organic chemistry, and suggest how it discriminates between substrates and controls reaction of its highly reactive ferryl intermediate. The presence of an unpredicted jelly roll beta-barrel core in CAS implies divergent evolution within the family of 2OG and related oxygenases. Comparison with other non-heme oxidases/oxygenases reveals flexibility in the position which dioxygen ligates to the iron, in contrast to the analogous heme-using enzymes.
Zhang
Z
Z
The Dyson Perrins Laboratory and the Oxford Centre for Molecular Sciences, South Parks Road, Oxford OX1 3QY, UK.
Ren
J
J
Stammers
D K
DK
Baldwin
J E
JE
Harlos
K
K
Schofield
C J
CJ
D001120:Arginine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D001372:Aza Compounds / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000737:chemistry / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D010100:Oxygen / Q000378:metabolism; D011487:Protein Conformation; D013379:Substrate Specificity
D001372:Aza Compounds; D007527:Isoenzymes; D007656:Ketoglutaric Acids; C066045:proclavaminic acid; D001120:Arginine; D007501:Iron; D006899:Mixed Function Oxygenases; C066046:clavaminate synthase; D010100:Oxygen; C000015:N-acetyl-L-arginine