Suppression of the ribosomal L2 gene reveals a novel mechanism for stress adaptation in soybean.
Pseudomonas syringae pv. glycinea bacteria or zoospores of the fungus Phytophthora sojae were used to trigger a hypersensitive reaction (HR) in cell cultures of soybean (Glycine max [L.] Merr. cv. Williams 82). During a screen for genes that show an altered expression as a response to dying neighbour cells we have identified a gene fragment that is specifically but transiently down-regulated in an HR. The corresponding cDNA codes for the ribosomal protein L2 (rpL2) of 80S ribosomes, which is essential for the peptidyl-transferase activity. Two gene copies of rpL2 exist in soybean and both genes are transcribed. The temporary down-regulation of the rpL2 genes is followed by a transient block in the synthesis of new proteins as visualised by pulse-labelling experiments using 35S-amino acids. The same basic phenomenon was also found after treatment of soybean cells with other stress-causing compounds such as elicitors or heavy metals. It is suggested that the transient block in protein synthesis allows a more rapid depletion of, for example, signal molecules with a short half-life time and thus leads to a faster adaptation of the cellular protein inventory to the new environmental conditions.
Ludwig
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A
Universität Kaiserslautern, FB Biologie, Geb. 22, 67663 Kaiserslautern, Germany.
Tenhaken
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R
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D002478:Cells, Cultured; D060365:Chloroplast Proteins; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005998:Glycine / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D010458:Peptidyl Transferases / Q000235:genetics / Q000378:metabolism; D010838:Phytophthora / Q000472:pathogenicity; D010940:Plant Proteins; D014176:Protein Biosynthesis; D011549:Pseudomonas / Q000472:pathogenicity; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D017385:Sequence Homology; D013025:Glycine max / Q000235:genetics / Q000382:microbiology / Q000502:physiology*
D060365:Chloroplast Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D012269:Ribosomal Proteins; C029466:ribosomal protein L2; D010458:Peptidyl Transferases; D005998:Glycine