Patterns of protein synthesis and tolerance of anoxia in root tips of maize seedlings acclimated to a low-oxygen environment, and identification of proteins by mass spectrometry.

摘要

Tolerance of anoxia in maize root tips is greatly improved when seedlings are pretreated with 2 to 4 h of hypoxia. The patterns of protein synthesis during hypoxic acclimation and anoxia are described. The incorporation of [35S]methionine into totalprotein and 262 individual proteins under different oxygen tensions was quantified. Proteins synthesized most rapidly under normoxic conditions continued to account for most of the proteins synthesized during hypoxic acclimation, while the production ofa very few proteins was selectively enhanced. When acclimated root tips were placed under anoxia, protein synthesis was depressed and no "new" proteins were detected. Evidence is presented that protein synthesis during acclimation, but not during subsequent anoxia, is crucial for acclimation. The complex and quantitative changes in protein synthesis during acclimation necessitate identification of large numbers of individual proteins. Mass spectrometry can be effectively used to identify plant proteinsarrayed by two-dimensional gel electrophoresis. Of the 48 protein spots analysed, 46 were identified by matching to the protein database. The expression of proteins involved in a wide range of cellular functions is described, including previously reported anaerobic proteins, and their possible roles in adaptation of plants to low-oxygen stress are discussed.