Genetic analysis of pathway regulation for enhancing branched-chain amino acid biosynthesis in plants
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Desert Agriculture Initiative
Plant Stress Genomics Research Lab
Online Publication Date2010-08-12
Print Publication Date2010-08
Permanent link to this recordhttp://hdl.handle.net/10754/561514
MetadataShow full item record
AbstractThe branched-chain amino acids (BCAAs) valine, leucine and isoleucine are essential amino acids that play critical roles in animal growth and development. Animals cannot synthesize these amino acids and must obtain them from their diet. Plants are the ultimate source of these essential nutrients, and they synthesize BCAAs through a conserved pathway that is inhibited by its end products. This feedback inhibition has prevented scientists from engineering plants that accumulate high levels of BCAAs by simply over-expressing the respective biosynthetic genes. To identify components critical for this feedback regulation, we performed a genetic screen for Arabidopsis mutants that exhibit enhanced resistance to BCAAs. Multiple dominant allelic mutations in the VALINE-TOLERANT 1 (VAT1) gene were identified that conferred plant resistance to valine inhibition. Map-based cloning revealed that VAT1 encodes a regulatory subunit of acetohydroxy acid synthase (AHAS), the first committed enzyme in the BCAA biosynthesis pathway. The VAT1 gene is highly expressed in young, rapidly growing tissues. When reconstituted with the catalytic subunit in vitro, the vat1 mutant-containing AHAS holoenzyme exhibits increased resistance to valine. Importantly, transgenic plants expressing the mutated vat1 gene exhibit valine tolerance and accumulate higher levels of BCAAs. Our studies not only uncovered regulatory characteristics of plant AHAS, but also identified a method to enhance BCAA accumulation in crop plants that will significantly enhance the nutritional value of food and feed. © 2010 Blackwell Publishing Ltd.
SponsorsWe thank Drs Leslie Hicks and Sophie Alvarez at the Danforth Plant Science Center for helping with amino acid quantification, and Dr Jian-Kang Zhu for critical reading of the manuscript. K. S. was supported by a National Science Foundation Research Experience for Undergraduates internship (grant number 0521250 to L. X). This study was supported by United States Department of Agriculture National Research Initiative competitive grant number 2004-02111 and the Monsanto Company (to L. X.).
JournalThe Plant Journal
- Acetolactate synthase regulatory subunits play divergent and overlapping roles in branched-chain amino acid synthesis and Arabidopsis development.
- Authors: Dezfulian MH, Foreman C, Jalili E, Pal M, Dhaliwal RK, Roberto DK, Imre KM, Kohalmi SE, Crosby WL
- Issue date: 2017 Apr 7
- Analysis of acetohydroxyacid synthase variants from branched-chain amino acids-producing strains and their effects on the synthesis of branched-chain amino acids in Corynebacterium glutamicum.
- Authors: Guo Y, Han M, Xu J, Zhang W
- Issue date: 2015 May
- Molecular identification of a further branched-chain aminotransferase 7 (BCAT7) in tomato plants.
- Authors: Kochevenko A, Klee HJ, Fernie AR, Araújo WL
- Issue date: 2012 Mar 15
- Mutations in the regulatory subunit of yeast acetohydroxyacid synthase affect its activation by MgATP.
- Authors: Lee YT, Duggleby RG
- Issue date: 2006 Apr 15
- A nuclear-encoded mitochondrial gene AtCIB22 is essential for plant development in Arabidopsis.
- Authors: Han L, Qin G, Kang D, Chen Z, Gu H, Qu LJ
- Issue date: 2010 Oct