Research
My laboratory is interested in using a molecular genetic approach to study the regulation of plant metabolism. We have isolated several mutants of the crucifer Arabidopsis thaliana that carry mutations in the genes encoding key regulatory enzymes involved in the biosynthesis of the branched-chain amino acids, isoleucine, valine, and leucine. Several mutant alleles encoding for acetolactate synthase (csr1-3 and csr1-4) and for threonine dehydratase/deaminase (omr1) have been isolated, characterized and a few such mutations have led to overproduction of free amino acids. Recently, we have isolated and characterized full length cDNAs for isopropylmalate synthase (IPMS), the regulatory enzyme of leucine biosynthesis. We are currently characterizing IPMS at the molecular and biochemical levels. In addition, we have also used a mutation induction approach to study the uptake and salvage of pyrimidine bases and their nucleosides. A new uracil transporter locus FOR1 has been isolated by selecting Arabidopsis mutants resistant to fluoroorotic acid. The Arabidopsis mutant for1/for1 has been characterized.
A new area of research in my laboratory is the use of mutant or transgenic plants in the extraction and uptake of lead from contaminated soil (phytoremediation). We are interested in identifying promoters and mutant genes that enhances a plant's ability to uptake, translocate and accumulate lead from soil.
|
|
F2 progeny of the cross FOR1/FOR1 X for1/for1 segregating for fluoroorotic acid resistance as a single recessive gene (3 sensitive: 1 resistant). Growing medium contains fluoroorotic acid and resistant plants are able to grow normal shoots and roots. |
| Arabidopsis transformants selected based on expressing the dominant selectable marker csr1-3 (triazolopyrimidine resistance). Positive transformants are easily observed at the cotyledonous stage immediately after germination displaying normal green cotyledons and normal roots among the dead sensitive non-transformants. omr1 and csr1-4 (not shown here) are also strong dominant selectable markers for plant transformation. |
|
|
One of our newly isolated promoters fused to GUS and showing strong expression in root tips, shoot tips and the reproductive cells of the flower. |
Publications
Mansfield T.A., Schultes N.P., Mourad G.S. (2009) AtAzg1 and AtAzg2 comprise a novel family of purine transporters in Arabidopsis. FEBS Lett 583: 481-486.
Mourad G.S., Snook B.S., Prabhakar J.T., Mansfield T.A., Schultes N.P. (2006) A fluoroorotic acid-resistant mutant of Arabidopsis defective in the uptake of uracil. J Exp Bot 57: 3563-3573.
Garcia E.L., Mourad G.S. (2004) A site-directed mutagenesis interrogation of the carboxy-terminal end of Arabidopsis thaliana threonine dehydratase/deaminase reveals a synergistic interaction between two effector-binding sites and contributes to the development of a novel selectable marker. Plant Mol Biol 54: 121-134.
Mourad G.S., inventor. Issued, 24 July, 2003. Methods and compositions for producing plants that express feedback insensitive threonine dehydratase/deaminase. Australian Patent No. 759068.
Mourad G.S., inventor. 15 April, 2003. Methods and compositions for producing plants that express feedback insensitive threonine dehydratase/deaminase. US Patent Application No. 10/413,943.
Mourad G.S., Junk D.J., inventors. 27 November 2002. Selection and use of isopropylmalate synthase (IPMS) mutants desensitized in L-leucine negative feedback regulation. US Patent Application No. 10/306,905
Mourad G.S., inventor. Issued, 13 May, 2002. Methods and compositions for producing plants that express feedback insensitive threonine dehydratase/deaminase. New Zealand Patent No. 502301.
Junk D., Mourad G. (2002) Isolation and expression analysis of the isopropylmalate synthase gene family of Arabidopsis thaliana. J Exp Bot 53: 2453-2454.
Mourad G., Emerick R., Smith A. (2000) Molecular cloning and sequencing of a cDNA encoding an isoleucine feedback insensitive threonine dehydratase/deaminase of Arabidopsis thaliana line GM11b (Accession No. AF177212). (PGR00-20). Plant Physiol 122:619.
Mourad G., Emerick R., Marion A., Smith A. (1998) Cloning and sequencing of a cDNA encoding threonine dehydratase/deaminase of Arabidopsis thaliana (Accession No. AF096281). (PGR98-199) Plant Physiol 118:1534.
Mourad G. (1998) Chloroplast DNA isolation. In: Martinez-Zapater J.M. and Salinas J. (eds). Methods in Molecular Biology, Vol 82, Humana Press, Totawa, Madrid, pp. 71-77.
Mourad G., King J. (1995) L-O-methylthreonine-resistant mutant of Arabidopsis defective in isoleucine feedback regulation. Plant Physiol 107:43-52.
Mourad G., Williams D., King J. (1995) A double mutant allele, csr1-4, of Arabidopsis encodes an acetolactate synthase with altered kinetics. Planta 196:64-68.
Hattori J., Brown D., Mourad G., Labbé, H., Ouellet T., Sunohara G., Rutledge R., King J., Miki B. (1995) An acetohydroxyacid synthase mutant reveals a single point mutation involved in multiple herbicide resistance. Mol Gen Genet 246:419-425.
Ouellet T., Mourad G., Brown D., King J., Miki B. (1994) Regulation of acetohydroxyacid synthase activity levels in transgenic tobacco. Plant Sci 102:91-97.
Mourad G., Haughn G., King J. (1994) Intragenic recombination in the CSR1 locus of Arabidopsis. Mol Gen Genet 243:178-184.
Mourad G., King J. (1994) Somatic hybridization in Datura. In: Bajaj Y.P.S. (ed). Biotechnology in Agriculture and Forestry. Springer-Verlag, Berlin, New York, pp. 360-371.
Wu K., Mourad G., King J. (1994) A valine-resistant mutant of Arabidopsis thaliana displays an acetolactate synthase with altered feedback control. Planta 192:249-255.
Mourad G., Pandey B., King J. (1993) Isolation and genetic analysis of a triazolopyrimidine-resistant mutant of Arabidopsis. J Hered 84:91-96.
Mourad G.S., White J. (1992) The isolation of apparently homoplastidic mutants induced by a nuclear recessive gene in Arabidopsis thaliana. Theor Appl Genet 84:906-914.
Mourad G., King J. (1992) Effects of four classes of herbicides on the growth and acetolactate synthase activity in several variants of Arabidopsis thaliana. Planta 188:491-497.
Du X.D., Mourad G., Williams D., King J. (1991) Somatic hybrids derived from a fusion of a universal hybridizer and a wild type line of Datura. Plant Sci 79:111-118.
Mourad G., Polacco M., Robertson D., Morris D. (1989) A maternally inherited mutant of Zea mays L. lacks the cytochrome b/f complex. Current Genet 16:109-116.
Mourad G., Polacco M. (1989) Mini-Preparation of highly purified chloroplast DNA from maize. Plant Mol Biol Report 7:78-84.
Nawar M., Mourad G., Hamza H., Fahmy A. (1979) Differential sensitivity of Allium cepa and Drosophila melanogaster to the mutagenicity of maleic hydrazide. Egypt J Genet Cytol 8:167-174.
