Wörsdörfer B, Lingaraju M, Yennawar NH, Boal AK, Krebs C, Bollinger JM Jr, Pandelia ME. Organophosphonate-degrading PhnZ reveals an emerging family of HD domain mixed-valent diiron oxygenases.
Proc Natl Acad Sci U S A 2013;
110:18874-9. [PMID:
24198335 DOI:
10.1073/pnas.1315927110]
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Abstract
The founding members of the HD-domain protein superfamily are phosphohydrolases, and newly discovered members are generally annotated as such. However, myo-inositol oxygenase (MIOX) exemplifies a second, very different function that has evolved within the common scaffold of this superfamily. A recently discovered HD protein, PhnZ, catalyzes conversion of 2-amino-1-hydroxyethylphosphonate to glycine and phosphate, culminating a bacterial pathway for the utilization of environmentally abundant 2-aminoethylphosphonate. Using Mössbauer and EPR spectroscopies, X-ray crystallography, and activity measurements, we show here that, like MIOX, PhnZ employs a mixed-valent Fe(II)/Fe(III) cofactor for the O2-dependent oxidative cleavage of its substrate. Phylogenetic analysis suggests that many more HD proteins may catalyze yet-unknown oxygenation reactions using this hitherto exceptional Fe(II)/Fe(III) cofactor. The results demonstrate that the catalytic repertoire of the HD superfamily extends well beyond phosphohydrolysis and suggest that the mechanism used by MIOX and PhnZ may be a common strategy for oxidative C-X bond cleavage.
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