4u5p

Publication Abstract from PubMed

The vast majority of characterized oxygenases use bound cofactors to activate molecular oxygen to carry out oxidation chemistry. Here, we show that an enzyme of unknown activity, RhCC from Rhodococcus jostii RHA1, functions as an oxygenase, using 4-hydroxyphenylenolpyruvate as a substrate. This unique and complex reaction yields 3-hydroxy-3-(4-hydroxyphenyl)-pyruvate, 4-hydroxybenzaldehyde, and oxalic acid as major products. Incubations with H2(18)O, (18)O2, and a substrate analogue suggest that this enzymatic oxygenation reaction likely involves a peroxide anion intermediate. Analysis of sequence similarity and the crystal structure of RhCC (solved at 1.78 A resolution) reveal that this enzyme belongs to the tautomerase superfamily. Members of this superfamily typically catalyze tautomerization, dehalogenation, or decarboxylation reactions rather than oxygenation reactions. The structure shows the absence of cofactors, establishing RhCC as a rare example of a redox-metal- and coenzyme-free oxygenase. This sets the stage to study the mechanistic details of cofactor-independent oxygen activation in the unusual context of the tautomerase superfamily.

Functional and structural characterization of an unusual cofactor-independent oxygenase.,Baas BJ, Poddar H, Geertsema EM, Rozeboom HJ, de Vries MP, Permentier HP, Thunnissen AM, Poelarends GJ Biochemistry. 2015 Feb 10;54(5):1219-32. doi: 10.1021/bi501200j. Epub 2015 Jan, 22. PMID:25565350^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.