Organophosphonate-degrading PhnZ reveals an emerging family of HD domain mixed-valent diiron oxygenases.
Worsdorfer, B., Lingaraju, M., Yennawar, N.H., Boal, A.K., Krebs, C., Bollinger, J.M., Pandelia, M.E.(2013) Proc Natl Acad Sci U S A 110: 18874-18879
- PubMed: 24198335 
- DOI: https://doi.org/10.1073/pnas.1315927110
- Primary Citation of Related Structures:  
4N6W, 4N71 - PubMed 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.
Organizational Affiliation: 
Departments of Chemistry, and Biochemistry and Molecular Biology, and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.