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

Abstract

Tolerance of anoxia in maize root tips is greatly improved when seedlings are pretreated with 2 to 4 h of hypoxia. We describe the patterns of protein synthesis during hypoxic acclimation and anoxia. We quantified the incorporation of [35 S]methionine into total protein and 262 individual proteins under different oxygen tensions. Proteins synthesized most rapidly under normoxic conditions continued to account for most of the proteins synthesized during hypoxic acclimation, while the production of a very few proteins was selectively enhanced. When acclimated root tips were placed under anoxia, protein synthesis was depressed and no "new" proteins were detected. We present evidence 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. We show that mass spectrometry can be effectively used to identify plant proteins arrayed by two-dimensional gel electrophoresis. Of the 48 protein spots analyzed, 46 were identified by matching to the protein database. We describe the expression of proteins involved in a wide range of cellular functions, including previously reported anaerobic proteins, and discuss their possible roles in adaptation of plants to low-oxygen stress.

Expanding the organismal scope of proteomics: Cross‐species protein identification by mass spectrometry and its implications

“…However, using MS and advanced methods of database interrogation, it is becoming increasingly possible to study the proteomes of organisms with unsequenced genomes. Cross-species identifications have been made in these organisms and others not cited: Zea mays [46,47], Pisum sativum [48,49], Papaver somniferum [50], Spinacia oleracea [44], Arabidopsis thaliana [44], Bos taurus [51], Xenopus laevis [30,52], Pichia pastoris [25], and Trypanosoma brucei [28,29]. Many earlier studies utilizing cross-species identification of unknown proteins relied on high mass accuracy MALDI peptide mapping, and therefore may have identified proteins or enzymes highly conserved across the biosphere.…”

“…With the application of MS and sequence similarity methods, a single sequenced genome will enable the identification of more proteins from the proteomes of organisms with unsequenced genomes than by the use of methods that are only able to identify proteins of high homology to database entries. For example, all cross-species identifications in the study of the maize proteome by Chang et al [46] could have been accomplished using database entries from the Arabidopsis genome and sequence similarity searches ( Table 2). Protein sequences from organisms in the left column were used to identify maize proteins by peptide mass mapping.…”

Transcriptional and post-transcriptional regulation of gene expression in submerged root cells of maize

“…[21][22][23] Subsequently, the accumulations of ANPs were shown to be tightly associated with efficient loading of anaerobically responsive transcripts with polysomes. Although a large number of aerobic transcripts are also induced in response to oxygen deprivation, fewer aerobic transcripts are loaded with ribosomes.…”

“…By contrast, a small group of abiotic and biotic stress-induced mRNAs showed a significant increase in polysome association, without a change in abundance. 23,26 Evaluation of mRNA sequences demonstrated that a low GC nucleotide content of the 5'-untranslated region provides a selective advantage for translation under low oxygen. 23,26 These evidences demonstrate that selected synthesis of anaerobic polypeptides involves transcriptional, as well as significant post-transcriptional, regulation of gene expression.…”

Impact of solar Ultraviolet-B on the proteome in soybean lines differing in flavonoid contents

“…Combined with mass spectrometry (MS), it allows rapid and reliable protein identification and can provide information about abundance and PTM. In recent years, proteomic-based technologies have been successfully applied to the systematic study of the proteomic responses in many plant species to a wide range of abiotic stresses, including drought (Pinheiro et al, 2005), nutrition deficiency (Alves et al, 2006), temperature (Yan et al, 2006;Sule et al, 2004), oxidative stress (Wang et al, 2004), herbicide (Castro et al, 2005), wound (Shen et al, 2003), anoxia (Chang et al, 2000), salt (Yan et al, 2005) and heavy metal (Labra et al, 2006). Casati et al (2005) have used proteomic technologies to investigate the effects of UV-B on the proteome of the maize leaf.…”