A point mutation converts dihydroneopterin aldolase to a cofactor-independent oxygenase.
Dihydroneopterin aldolase (DHNA) catalyzes the conversion of 7,8-dihydroneopterin (1) to 6-hydroxymethyl-7,8-dihydropterin (4) in the folate biosynthetic pathway. Substitution of a conserved tyrosine residue at the active site of DHNA by phenylalanine converts the enzyme to a cofactor-independent oxygenase, which generates mainly 7,8-dihydroxanthopterin (6) rather than 4. 6 is generated via the same enol intermediate as in the wild-type enzyme-catalyzed reaction, but this species undergoes an oxygenation reaction to form 6. The conserved tyrosine residue plays only a minor role in the formation of the enol reaction intermediate but a critical role in the protonation of the enol intermediate to form 4.
Wang
Yi
Y
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824, USA.
Scherperel
Gwynyth
G
Roberts
Kade D
KD
Jones
A Daniel
AD
Reid
Gavin E
GE
Yan
Honggao
H
D000446:Aldehyde-Lyases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010105:Oxygenases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017354:Point Mutation; D021241:Spectrometry, Mass, Electrospray Ionization; D013329:Structure-Activity Relationship
D010105:Oxygenases; D000446:Aldehyde-Lyases; C020044:dihydroneopterin aldolase; D010100:Oxygen