| Abstract Detail
Metabolic Engineering Barrow, Matthew [1], Bagga, Suman [2], Sengupta-Gopalan, Champa [3]. The effect of increasing free methionine pools on the expression of the different genes in methionine metabolism in the leaves and nodules of alfalfa. Methionine (Met) is an essential amino acid and animals depend on plants to obtain Met. Our preliminary results indicate that alfalfa, an important forage crop, is low in free Met pools. One of our objectives is to increase the free Met pools of alfalfa by manipulating Met metabolism. The synthesis of Met starts with O-phosphohomo-Ser (OPH). Cystathionine γ-synthase (CγS) converts OPH into cystathionine, which is the first committed step of Met biosynthesis while Thr synthase (TS) converts OPH into Thr. The major route for Met metabolism is in the synthesis of S-adenosyl methionine (SAM) catalyzed by SAM synthase (SAMS). SAM is the major methyl group donor and is the precursor for polyamines and ethylene. Met is also metabolized into S-methylmethionine (SMM), catalyzed by Met S-methyltransferase (MMT) and can be reconverted to Met by homo-Cys S-methyltransferase (HMT). The goal of this research is to understand how increasing free Met pools by overexpressing CγS will affect the expression of genes in the Met metabolic pathway in the leaves and nodules of alfalfa. RNA analysis indicates a decrease in the expression of endogenous CγS, SAMS, and TS in the leaves of alfalfa overexpressing the Arabidopsis CγS gene, while there was no observable change in the nodules. Results also indicate increased expression of MMT transcript in the leaves of transgenic alfalfa. Experiments are in progress to check expression of genes in polyamine and ethylene synthesis in alfalfa plants expressing the CγS transgene. To check if increased free Met pools have any effect on the accumulation of Met-rich proteins, experiments are being conducted to compare the total protein profile between control and transgenic alfalfa.
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1 - New Mexico State University, Molecular Biology Program, Department of Plant and Environmental Sciences, Skeen Hall: 127N, Corner of College and Knox St., Las Cruces, NM, 88003, United States
2 - New Mexico State University, Department of Plant and Environmental Sciences
3 - New Mexico State University, Molecular Biology Program, Department of Plant and Environmental Sciences
Keywords:
Methionine
cystathionine gamma-synthase
alfalfa.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P43009
Abstract ID:2114 |
