Biochemical and immunological characterization of rice homologues of the human immunodeficiency virus-1 Tat binding protein and subunit 4 of human 26S proteasome subunits.
Previously, we isolated two cDNA clones, TBPOs-1 and TBPOs-2, encoding putative ATPases that are the rice homologues of human immunodeficiency virus-1 (HIV-1) Tat binding protein-1 and subunit 4 of human 26S proteasome. In order to determine the RNA-dependent ATPase activity of these putative proteins, the subclones from these cDNA clones were expressed in Escherichia coli as fusion proteins with maltose-binding protein. The recombinant proteins stimulated ATP hydrolysis in the presence of poly(U) and rice total RNA. In contrast, single- and double-stranded forms of HindIII-digested lambda phage DNA are less effective at stimulating ATP hydrolysis. Western blot analysis using antisera against the TBPOs proteins showed a widespread appearance of these proteins in rice tissues and cultured cells. The TBPOs proteins were also found around the region where rice proteasomes would sediment. In addition, the TBPOs-1 protein bound to tobacco TATA-binding protein in vitro. Thus, we suggest that the TBPOs proteins are novel RNA-dependent ATPases characteristic of DEAD-box proteins and propose that the TPBOs proteins can exist in rice proteasomes. Further, the TBPOs-1 protein is thought to play a role in transcriptional events.
Suzuka
I
I
Department of Molecular Genetics, National Institute of Agrobiological Resources, Tsukuba, Ibaraki, Japan.
Yanagawa
Y
Y
Yamazaki
K
K
Ueda
T
T
Nakagawa
H
H
Hashimoto
J
J
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D015497:HIV-1 / Q000737:chemistry*; D006801:Humans; D012275:Oryza / Q000737:chemistry*; D010447:Peptide Hydrolases / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; C064757:PSMC3 protein, human