Characterization of Hypoxically Inducible Lactate Dehydrogenase in Maize.
AUTOR(ES)
Christopher, M. E.
RESUMO
Oxygen deprivation induces a wide variety of genes, but the most extensively studied are those encoding enzymes of the glycolytic pathway. Lactate dehydrogenase (LDH, EC 1.1.1.27) activity increases up to 3.5-fold in maize (Zea mays L.) roots during several days of hypoxic induction. This increase in activity is accompanied by a decrease in in vitro enzyme stability. LDH activity in aerobic root extracts has an in vitro half-life of 240 min, decreasing to 100 min in 72-h hypoxically induced plant root extracts. The increase in enzyme activity during hypoxic induction is the result of increased protein levels, which correlate with increased transcript levels. Two ldh transcripts of 1.3 and 1.7 kb are induced, with maximum levels reached by 8 and 24 h, respectively. This suggests that the two ldh genes are differentially regulated. Treatment with the protein synthesis inhibitor cycloheximide does not preclude ldh induction during the first few hours of hypoxic stress, suggesting that new protein synthesis may not be essential for elevation of ldh transcript levels under hypoxic conditions. The rapid and substantial increase in ldh mRNA levels under hypoxic conditions and in the presence of cycloheximide suggests that the ldh gene may be valuable in analyzing the hypoxic signal transduction pathway.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=158028Documentos Relacionados
- Hypoxically inducible barley lactate dehydrogenase: cDNA cloning and molecular analysis.
- Purification and Properties of Hypoxically Induced Lactate Dehydrogenase from Barley Roots 1
- Purification, Characterization, and Submitochondrial Localization of the 32-Kilodalton NADH Dehydrogenase from Maize.
- Purification and Characterization of the Bifunctional Enzyme Lysine-Ketoglutarate Reductase-Saccharopine Dehydrogenase from Maize.
- Malate dehydrogenase: viability of cytosolic nulls and lethality of mitochondrial nulls in maize.