Dept. of Biological Sciences

Robert P. Lawther

Associate Professor of Biological Sciences
Ph.D., 1974, University of Pittsburgh
803-777-6792
lawther@biol.sc.edu

Director, Oligonucleotide Synthesis Laboratory

Biochemistry, Molecular Biology, Biochemical Genetics

Growth of an organism depends upon achieving an optimal balance among the various cellular processes. It is estimated that the bacteria Escherichia coli K-12 converts as much as 10% of the glucose utilized for its growth to the amino acids isoleucine, leucine and valine. Thus, the synthesis of these three amino acids represents a substantial investment of cellular resources, and therefore presumably their biosynthesis is tightly regulated. Because these three amino acids share a common biochemical pathway, the cell utilizes both genetic and biochemical regulation to achieve the necessary balance among these amino acids. The genes for the enzymes are divided into five clusters each regulated by different signals. Also, specific enzymes are allosterically affected by an individual amino acid to modulate the flow of intermediates through the pathway. Our research group studies the ilvGMEDA operon the largest of the gene clusters. Currently, our efforts are to assess both the transcriptional effectors of these genes and the structural elements of the enzyme threonine deaminase that result in its allosteric regulation by isoleucine feedback inhibition.

Selected Publications:

Lopes, J.M. and R.P. Lawther. 1989. Physical identification of an internal promoter, ilvAp, in the distal portion of the ilvGMEDA operon. Gene 76:255-269.

Lopes, J.M., N. Soliman, P.K. Smith, and R.P. Lawther. 1989. Transcriptional polarity enhances the contribution of the internal promoter, ilvEp, in the expression of the ilvGMEDA operon in wild type Escherichia coli K-12. Molec. Microbiol. 3:1039-1051.

Lawther, R.P., J.M. Lopes, M.J. Ortuno, and M.C. White. 1990. Analysis of the regulation of the ilvGMEDA operon using leader- attenuator-galK gene fusions. J. Bacteriol. 172:2320-2327.

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