Lysine accumulation in maize cell cultures transformed with a lysine-insensitive form of maize dihydrodipicolinate synthase

Lysine is one of the nutritionally limiting amino acids in food and feed products made from maize (Zea mays L.). Two enzymes in the lysine biosynthesis pathway, aspartate kinase (AK) and dihydro-dipicolinate synthase (DHPS), have primary roles in regulating the level of lysine accumulation in plant...

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Published in:Theoretical and applied genetics 1996, Vol.92 (1), p.70-77
Main Authors: Bittel, D.C, Shaver, J.M, Somers, D.A, Gengenbach, B.G. (Minnesota Univ., St. Paul (USA). Dept. of Agronomy and Plant Gentics)
Format: Article
Language:English
Subjects:
Biological and medical sciences
Classical genetics, quantitative genetics, hybrids
CULTIVO DE CELULAS
CULTURE DE CELLULE
Fundamental and applied biological sciences. Psychology
Genetics of eukaryotes. Biological and molecular evolution
LIGASAS
LIGASE
LISINA
LYSINE
Pteridophyta, spermatophyta
TRANSFERASAS
TRANSFERASE
TRANSFORMACION GENETICA
TRANSFORMATION GENETIQUE
Vegetals
ZEA MAYS
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Summary:Lysine is one of the nutritionally limiting amino acids in food and feed products made from maize (Zea mays L.). Two enzymes in the lysine biosynthesis pathway, aspartate kinase (AK) and dihydro-dipicolinate synthase (DHPS), have primary roles in regulating the level of lysine accumulation in plant cells because both enzymes are feedback-inhibited by lysine. An isolated cDNA clone for maize DHPS was modified to encode a DHPS much less sensitive to lysine inhibition. The altered DHPS cDNA was transformed into maize cell suspension cultures to determine the effect on DHPS activity and lysine accumulation. Partially purified DHPS (wildtype plus mutant) from transformed cultures was less sensitive to lysine inhibition than wildtype DHPS from nontransformed cultures. Transformed cultures had cellular free lysine levels as much as four times higher than those of nontransformed controls. Thus, we have shown that reducing the feedback inhibition of DHPS by lysine can lead to increased lysine accumulation in maize cells. Increasing the capacity for lysine synthesis may be an important step in improving the nutritional quality of food and feed products made from maize.
ISSN:0040-5752
1432-2242
DOI:10.1007/BF00222953