Mary Schuler

 

Professor of Cell and Developmental Biology, Plant Biology, and Biochemistry
Program in Physiology & Molecular Plant Biology
161 Edward R. Madigan Laboratory,

1201 W. Gregory Drive MC-051
(217) 333-8784

Education

B.A., 1974 Cornell University
Ph.D., 1981 Cornell University
Postdoc, 1981-1983 Washington University

Teaching

MCB316, Introduction to Eukaryotic Molecular Genetics

Research Overview

One focus of the research in my laboratory is aimed at understanding the factors that influence the removal of introns from pre-mRNAs in plant nuclei and defining the mechanism for intron excision. Although it might be logical to assume that plants and animals share common mechanisms for intron removal, in vivo and in vitro studies have demonstrated that the splicing machineries are not interchangeable between plants and animals or, for that matter, between dicot and monocot plants. Molecular analysis of the intron splice site requirements in plant nuclei using in vivo expression systems has allowed us to demonstrate that plant 5’ and 3’ splice site recognition depends on having strong AU-transition points between intron and exon that are used for their selection. Current projects are aimed at defining the range of splicing factors mediating constitutive and alternative splicing during plant growth and development. Using Arabidopsis T-DNA knockout/knockout lines and RNA silencing lines depleted for different classes of splicing factors, we are characterizing the role of a number of plant-specific splicing factors as well as general splicing factors. Using microarray genomic approaches, we are analyzing the range of transcripts affected by splicing factor inactivation. Coupled with our current knowledge on required cis-acting sequences, these molecular approaches will eventually identify the trans-acting factors involved in the recognition of plant and other AU-rich introns and - in the long run - help define the optimal sequences needed to express genes/proteins in transgenic plants.

 

The second major focus in my laboratory is aimed at defining the transcriptional elements regulating expression of plant and insect cytochrome P450 monooxygenase genes. In both plants and insects, these genes encode enzymes critical for synthesis of an array of hormones and defense compounds as well as the metabolism of hydroxylated products such as herbicides and insecticides. Because of this, their transcriptional regulatory cascades respond to natural and synthetic compounds, predators and pathogens in the environment. A variety of RT-PCR and microarray strategies are being used to define the range of plant (Arabidopsis thaliana, Zea mays) P450 genes induced in response to chemical and environmental stresses and the range of insect (Papilio polyxenes, Helicoverpa zea) P450 genes induced in response to plant signaling molecules and toxins. The elements regulating transcription are being identified using promoter:reporter gene fusions (CAT, LUC, GFP) in transgenic plants and in transfected insect cell cultures.

 

The third focus in my laboratory is aimed at developing molecular models of the catalytic sites in insect P450s metabolizing plant toxins and insecticides and in plant P450s synthesizing an array of secondary products. A variety of protein expression strategies using yeast and baculovirus systems and site-directed changes in catalytic site residues are being used to refine our molecular models and to predict alternate substrates for each of these P450s.

Recent Publications

Schuler, M.A. 2008. Splice site requirements and switches in plants. In "Nuclear pre-mRNA processing in plants"; A.S.N. Reddy, M. Golovkin, Eds.; Springer-Verlag.

 

Li, X., Schuler, M.A., and Berenbaum, M.R. 2007. Molecular mechanisms of metabolic resistance to synthetic and natural xenobiotics. Annu. Rev. Entomol. 52:231–53.

 

Li, X., Wen, Z., Bohnert, H.J., Schuler, M.A., and Kushad, M.M. 2007. Myrosinase in horseradish (Armoracia rusticana) root: Isolation of a full-length cDNA and its heterologous expression in Spodoptera frugiperda insect cells. Plant Sci., 172:1095–1102.

 

Mao, W., Berenbaum, M.R., and Schuler, M.A. 2008. Modifications in the N-terminus of an insect P450 enhance production of catalytically active protein in baculovirus-Sf9 cell expression systems. Insect Biochem. Mol. Biol. 38:66-75.

 

Mao, W., Rupasinghe, S., Zangerl, A., Berenbaum, M.R., and Schuler, M.A. 2007. Allelic variation in the Depressaria pastinacella CYP6AB3 protein enhances metabolism of plant allelochemicals by altering a proximal surface residue and potential interactions with cytochrome P450 reductase. J. Biol. Chem., 282:10544–52.

 

Mao, W., Schuler, M.A., and Berenbaum, M.R. 2007. Cytochrome P450s in Papilio multicaudatus and the transition from oligophagy to polyphagy in the Papilionidae. Insect Mol. Biol., 16:481–490.

 

Rupasinghe, S., Duan, H., and Schuler, M.A. 2007. Molecular definitions of fatty acid hydroxylases in Arabidopsis thaliana. Proteins, 68: 279–93.

 

Rupasinghe, S.G., Duan, H., Frericks Schmidt, H.L., Berthold, D., Rienstra, C.M., and Schuler, M.A. 2007. High-yield expression, purification and refolding of isotopically labeled cytochrome P450 monooxygenases for solid-state NMR spectroscopy. Biochim. Biophys. Acta 1768:3061-3070.

 

Rupasinghe, S., Schuler, M.A., Kagawa, N., Yuan, H., Lei, L., Zhao, B., Kelly, S.L., Waterman, M.R. and Lamb, D.C. 2007. The cytochrome P450 gene family CYP157 does not contain EXXR in the K-helix reducing the absolute conserved P450 residues to a single cysteine. FEBS Lett., 580:6338–6342.

 

Rupasinghe, S.G., Wen, Z., Chiu, T.L. and Schuler, M.A. 2007. Helicoverpa zea CYP6B8 and CYP321A1: different molecular solutions to the problem of metabolizing plant toxins and insecticides. Protein Eng. Des. Sel. 20:615–624.

 

Schuler, M.A. and Sligar, S.G. 2007. Diversities and similarities in P450 systems: an introduction. In "The ubiquitous roles of cytochrome P450 proteins", Vol. 3 of 'Metal Ions in Life Sciences'; A. Sigel, H. Sigel, R. K. O. Sigel, Eds.; John Wiley & Sons, Ltd., Chichester, UK. Pp. 1-26.

 

Zeng, R.S., Wen, Z., Niu, G., Schuler, M.A., and Berenbaum, M.R. 2007. Allelochemical induction of cytochrome P450 monooxygenases and amelioration of xenobiotic toxicity in Helicoverpa zea. J. Chem. Ecol., 33:449–461.