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Lynnette M.A. Dirk |
The co-translational enzyme, peptide deformylase (E.C. 3.5.1.88; DEF), hydrolyzes the N-formyl group from initiating methionines of nascent polypeptides in plant plastids and mitochondria (Dirk et al., 2001), in addition to eubacteria. The model plant, Arabidopsis thaliana has two DEFs encoded by its nuclear genome. The N-termini of the translated proteins target the enzymes to both organelles as we have determined by N-terminal full length fusions with green fluorescent protein and confocal microscopy (Dinkins et al., 2003); and yet, there are distinct specificities of the two DEFs regarding which chloroplast-translated proteins are efficiently processed (Dirk et al., 2002).
Our initial characterization of the functional significance of the enzyme to plants revealed that the well-characterized inhibitor, actinonin, during seed imbibition can, at a high enough concentration, completely inhibit the completion of germination (Dirk et al., 2001). Furthering this NSF-funding goal, we have characterized a decrease in chlorophyll fluorescence of actinonin-treated tobacco leaves and reduced D1 synthesis with isolated chloroplasts during a time course of actinonin treatment (Hou et al., 2004).
Further emphasis during this two year grant is on identifying any structural uniqueness of the active site of these eukaryotic enzymes by NMR spectroscopy and, more recently, crystallization. Such characters would be useful in developing plant-specific inhibitors to be functional as broad-spectrum herbicides without any detrimental effects on soil-borne or water table bacteria.
Relevant References
1. Hou C-X, Dirk LMA, and Williams MA. 2004. Inhibition of peptide deformylase in Nicotiana tabacum leads to decreased D1 protein accumulation and disassembly of PSII complexes. American Journal of Botany 91: 1304-1311.
2. Dinkins RD, Conn HM, Dirk LMA, Williams MA, and Houtz RL. 2003. The Arabidopsis thaliana peptide deformylase 1 protein is localized to both mitochondria and chloroplasts. Plant Science 165(4): 751-758.
3.
Dirk LMA, Williams MA, and Houtz RL. 2002. Specificity of
chloroplast-localized peptide deformylases as determined with peptide
analogs of chloroplast-translated proteins. Archives of Biochemistry
and Biophysics 406(1): 135-141.
4. Dirk LMA, Williams MA, and Houtz RL. 2001. Eukaryotic peptide
deformylases. Nuclear-encoded and chloroplast-targeted enzymes in
Arabidopsis. Plant Physiology 127(1): 97-107.
This page was created October 2004. This material is based upon work supported by the National Science Foundation under Grant No. 0240165. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Please send any comments to Lynnette Dirk.