Don P. Bourque. Professor, Department of Biochemistry. Ph.D., Duke University. Structure, function, and molecular biology of chloroplast ribosomes, molecular biology of nitrogen fixation, detoxification of xenobiotic-contaminated environments by genetically-engineered plants.

We study genes which code for tobacco chloroplast ribosomal proteins. Our research is aimed at understanding the coordination of expression of both nuclear and chloroplast genes involved in chloroplast ribosome biogenesis. We are: 1) examining rps12 gene expression, which requires a novel RNA processing event -trans-splicing of two different chloroplast DNA transcripts (both containing portions of the polypeptide coding regions) - to give a functional rps12 mRNA with its three exons in correct reading frames; 2) studying nuclear genes coding for chloroplast ribosomal proteins; and 3) examining mechanisms of regulation of expression of chloroplast ribosomal protein-coding genes.

Another project involves developing genetically-engineered plants to detoxify xenobiotics in the soil. Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants which are highly toxic, probably carcinogenic, and are now found in organisms throughout the food chain, including humans. A cytochrome P-450 (PBD-2) metabolizes highly chlorinated PCBs which are particularly persistent toxins in humans. We have sequenced a cDNA coding for PBD-2. Studying transgenic plants which express the PBD-2 gene, we are engineering them for constitutive expression of PBD-2, with particular interest in expression in roots. Electron transfer between PBD-2 and plant P-450 reductase in transgenic plants may result in detoxification of PCBs. Dispersal of transgenic plants in PCB-contaminated sites will be avoided by engineering male sterile plants which express PBD-2.

D.W. Galbraith, H.J. Bohnert, and D.P. Bourque, eds. Methods in Plant Cell Biology: Methods in Plant Cell Biology, volume 49, Academic Press. N.Y. 568pp. (1995).

D.W. Galbraith, D.P. Bourque, and H.J. Bohnert, eds. Methods in Cell Biology: Methods in Plant Cell Biology, volume 50, Academic Press, N.Y., 555pp. (1995).

G.A. Elhag and D.P. Bourque. Chloroplast ribosomal protein L27:Isolation and sequence analysis of cDNA clones from Nicotiana tabacum. Biochemistry 31 (1992) 6856-6864.

G.A. Elhag and D.P. Bourque. Nucleotide and deduced amino acid sequences of cDNAs coding for Nicotiana tabacum chloroplast ribosomal protein L24. Journal of Biological Chemistry 267 (1992) 21705-21711.

Elhag, G.A., F.J. Thomas, T.P. McCreery, and D.P. Bourque. 1992. Nuclear-encoded chloroplast ribosomal protein L12 of Nicotiana tabacum: characterization of mature protein and isolation and sequence of cDNA clones encoding its cytoplasmic precursor. Nucl. Acids Research 20:689-697.

Ciaccio, P.J., P.E. Graves, D.P. Bourque, B. Glinsman-Gibson, and J.R. Halpert. 1991. cDNA and deduced amino acid sequences of a dog liver cytochrome P450 of the IIIA gene subfamily. Biochim. Biophys. Acta. 1088:319-322.

Graves, P.E., G. Elhag, P.J. Ciaccio, D.P. Bourque, and J.R. Halpert. 1990. cDNA and deduced amino acid sequence of a dog hepatic cytochrome P450IIB responsible for the metabolism of 2,2', 4,4', 5,5'-hexachlorobiphenyl. Arch. Biochem. Biophys. 281:106-115.

Bonham-Smith, P.C., and D.P. Bourque. 1990. The chloroplast genome and regulation of its expression. In: Chromosomes: Eucaryotic, Procaryotic, and Viral. Volume II, CRC Press, Inc. pages 179-216.

Bonham-Smith, P.C., and D.P. Bourque. 1989. Translation of chloroplast-encoded mRNA: Potential initiation and termination signals. Nucl. Acids Res. 17:2057-2080.

Hildebrand, M., R.B. Hallick, C.W. Passavant, and D.P. Bourque. 1988. Trans-splicing in chloroplasts: The rps12 loci of Nicotiana tabacum. Proc. Natl. Acad. Sci. USA 85:372-376.