Molecular characterization of a beta-type proteasome subunit from Arabidopsis thaliana co-expressed at a high level with an alpha-type proteasome subunit early in the cell cycle.
Proteasomes are the essential components of complexes involved in an extralysosomal energy- and ubiquitin-dependent proteolytic pathway. The first alpha-type proteasome subunit in plants has recently been described. In this work, the sequence of the first beta-type proteasome subunit in plants, isolated from Arabidopsis thaliana cDNA libraries is reported. The mRNA accumulation of both subunits was analysed and compared with those of the ubiquitin and histone mRNAs, in different tissues and during re-initiation of mitotic activity. It is demonstrated that in plants, as in animal cells, the transcripts of both the alpha-type and beta-type proteasome subunits accumulate to high levels during cell proliferation, in parallel with mRNAs coding for a ubiquitin fusion protein and several polyubiquitins, but earlier than those coding for histone H4 whose expression is known to be coupled to DNA synthesis. These results suggest that, as in animal cells, proteasomes may be involved in the progression of the cell cycle.
Genschik
P
P
Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, Strasbourg, France.
Jamet
E
E
Philipps
G
G
Parmentier
Y
Y
Gigot
C
C
Fleck
J
J
D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002453:Cell Cycle; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000096:biosynthesis*; D018076:DNA, Complementary; D015870:Gene Expression; D015723:Gene Library; D017343:Genes, Plant; D006657:Histones / Q000096:biosynthesis; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000096:biosynthesis*; D005810:Multigene Family; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014452:Ubiquitins / Q000096:biosynthesis
D018076:DNA, Complementary; D006657:Histones; D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014452:Ubiquitins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex