Isotope labeling studies reveal the order of oxygen incorporation into the tryptophan tryptophylquinone cofactor of methylamine dehydrogenase.
The bacterial enzyme methylamine dehydrogenase (MADH) contains the protein-derived cofactor tryptophan tryptophylquinone (TTQ). TTQ is generated by the posttranslational modification of two endogenous MADH tryptophans, betaW57 and betaW108. Two oxygens are inserted sequentially into betaW57 to generate the quinone moiety, after which it is cross-linked to betaW108. We have previously shown that the second oxygenation and cross-link formation are catalyzed by the novel di-heme cytochrome MauG. Here we show, using isotopically labeled oxygen and water, that the first addition of oxygen occurs specifically at the C7 position of betaW57 and that MauG then inserts the second oxygen at position C6.
Pearson
Arwen R
AR
Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Marimanikkuppam
Sudha
S
Li
Xianghui
X
Davidson
Victor L
VL
Wilmot
Carrie M
CM
D002384:Catalysis; D045563:Indolequinones / Q000737:chemistry / Q000378:metabolism*; D007553:Isotope Labeling / Q000379:methods; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*; D010103:Oxygen Isotopes; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism
D045563:Indolequinones; D010103:Oxygen Isotopes; C070569:tryptophan tryptophylquinone; D014364:Tryptophan; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D010100:Oxygen