PMID- 19088070
OWN - NLM
STAT- MEDLINE
DCOM- 20090331
LR  - 20210206
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 284
IP  - 7
DP  - 2009 Feb 13
TI  - Identification of a gatekeeper residue that prevents dehydrogenases from acting 
      as oxidases.
PG  - 4392-7
LID - 10.1074/jbc.M808202200 [doi]
AB  - The oxygen reactivity of flavoproteins is poorly understood. Here we show that a 
      single Ala to Gly substitution in l-galactono-gamma-lactone dehydrogenase (GALDH) 
      turns the enzyme into a catalytically competent oxidase. GALDH is an 
      aldonolactone oxidoreductase with a vanillyl-alcohol oxidase (VAO) fold. We found 
      that nearly all oxidases in the VAO family contain either a Gly or a Pro at a 
      structurally conserved position near the C4a locus of the isoalloxazine moiety of 
      the flavin, whereas dehydrogenases prefer another residue at this position. 
      Mutation of the corresponding residue in GALDH (Ala-113 --> Gly) resulted in a 
      striking 400-fold increase in oxygen reactivity, whereas the cytochrome c 
      reductase activity is retained. The activity of the A113G variant shows a linear 
      dependence on oxygen concentration (k(ox) = 3.5 x 10(5) m(-1) s(-1)), similar to 
      most other flavoprotein oxidases. The Ala-113 --> Gly replacement does not change 
      the reduction potential of the flavin but creates space for molecular oxygen to 
      react with the reduced flavin. In the wild-type enzyme, Ala-113 acts as a 
      gatekeeper, preventing oxygen from accessing the isoalloxazine nucleus. The 
      presence of such an oxygen access gate seems to be a key factor for the 
      prevention of oxidase activity within the VAO family and is absent in members 
      that act as oxidases.
FAU - Leferink, Nicole G H
AU  - Leferink NG
AD  - Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA 
      Wageningen, The Netherlands.
FAU - Fraaije, Marco W
AU  - Fraaije MW
FAU - Joosten, Henk-Jan
AU  - Joosten HJ
FAU - Schaap, Peter J
AU  - Schaap PJ
FAU - Mattevi, Andrea
AU  - Mattevi A
FAU - van Berkel, Willem J H
AU  - van Berkel WJ
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20081216
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Amino Acids)
RN  - 0 (Arabidopsis Proteins)
RN  - 0 (Flavoproteins)
RN  - EC 1.1.- (Alcohol Oxidoreductases)
RN  - EC 1.1.3.38 (vanillyl-alcohol oxidase)
RN  - EC 1.3.- (Oxidoreductases Acting on CH-CH Group Donors)
RN  - EC 1.3.2.3 (galactonolactone dehydrogenase)
RN  - S88TT14065 (Oxygen)
SB  - IM
MH  - Alcohol Oxidoreductases/*chemistry/genetics
MH  - *Amino Acid Substitution
MH  - Amino Acids/chemistry/genetics
MH  - Arabidopsis/*enzymology/genetics
MH  - Arabidopsis Proteins/*chemistry/genetics
MH  - Flavoproteins/*chemistry/genetics
MH  - Mutation, Missense
MH  - Oxidation-Reduction
MH  - Oxidoreductases Acting on CH-CH Group Donors/*chemistry/genetics
MH  - Oxygen/chemistry
EDAT- 2008/12/18 09:00
MHDA- 2009/04/01 09:00
CRDT- 2008/12/18 09:00
PHST- 2008/12/18 09:00 [entrez]
PHST- 2008/12/18 09:00 [pubmed]
PHST- 2009/04/01 09:00 [medline]
AID - S0021-9258(20)71041-0 [pii]
AID - 10.1074/jbc.M808202200 [doi]
PST - ppublish
SO  - J Biol Chem. 2009 Feb 13;284(7):4392-7. doi: 10.1074/jbc.M808202200. Epub 2008 
      Dec 16.