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Y Takanami

Publications and source records attributed to Y Takanami.

29 records · Page 2Linked to original sources
PubMed1988

Effects of extra 5' non-viral bases on the infectivity of transcripts from a cDNA clone of satellite RNA (strain Y) of cucumber mosaic virus.

Full-length cDNA of a satellite RNA (Strain Y) which induces bright yellow symptoms on tobacco plants infected with cucumber mosaic virus (CMV) was cloned and sequenced. The published sequence of the satellite RNA was revised with three possible differences (residues 161, 167, and 173) and a nucleotide insertion at residue 234. The satellite cDNA was then inserted into a commercially available transcription vector. In vitro transcription products from the recombinant plasmid harbored 24 non-viral bases at their 5' ends and had very low infectivity when coinoculated with CMV. After removal of the extra 5' sequence of the transcripts with RNase H, the infectivity of the transcripts increased markedly. Analysis of the effects of extra 5' sequences of several lengths confirmed the importance of natural 5' ends for biological activity of the satellite. Trimming down to 6-9 extra bases at the 5' end enhanced the infectivity of the transcripts by 10-fold, although the specific activity of the natural satellite is still 100-fold higher. Dideoxynucleotide sequence analysis proved that the progeny satellite RNA did not retain the 24 non-viral bases at the 5' end of the transcript from pIBI 31-MC.

Amino Acid Sequence↗
PubMed1985

Messenger RNA structure participating in the initiation of synthesis of cucumber mosaic virus coat protein.

The sequence of the 5'-terminal 106 nucleotides of cucumber mosaic virus (strain Y) RNA 4, the mRNA coding for viral coat protein, has been determined. The first AUG was located at 77 nucleotides from the 5'-terminus and was confirmed to be an initiation codon by analysis of the N-terminal amino acid sequence of the protein. The nucleotide sequence (positions 77-106) beyond the AUG codon predicted the sequence of ten amino acids corresponding to the N-terminal region of the protein, which exactly matched the determined amino acid sequence containing an acetyl methionine as the N-terminal amino acid. The distance of the initiation codon AUG from the cap structure was 76 nucleotides and the longest among the mRNAs for coat protein of plant viruses so far reported (9-36 nucleotides). This noncoding region is rich in U residues (40%) and the number of G residues (21 nucleotides) is the largest among these mRNAs (usually 1 or 2 residues). A possible secondary structure is postulated for the region, which might be implicated in efficient translation of the RNA 4 in vivo.

Amino Acid Sequence↗
PubMed1983

Translation of satellite tobacco necrosis virus RNA modified by (not equal to)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene is inhibited in a wheat germ cell-free system.

It has been shown that (not equal to)-r-7-,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) modification of rabbit globin mRNA results in inhibition of translational initiation. In order to explore the possibility that modification of the 5' cap structure was responsible for this inhibition, the naturally non-capped mRNA from satellite tobacco necrosis virus (STNV) was reacted with BPDE and translated in a wheat germ cell-free system. The extent of modification was 1.3 and 2.9 BPDE residues/molecule. High performance liquid chromatography of the modified nucleosides from enzymatically hydrolyzed STNV RNA revealed that greater than 90% of the nucleoside adducts were substituted at the exocyclic amino group of guanosine. The translational ability of the lower and higher modified STNV, measured by incorporation of [14C]amino acids into acid-precipitable polypeptides is inhibited by 55% and 63%, respectively. Polyacrylamide gel electrophoretic analyses of the translation products indicate that predominantly full-length coat proteins are synthesized but with the carcinogen-modified STNV the amount is reduced. On the other hand, 80S initiation complex formation is not inhibited as measured by binding of the BPDE-modified STNV to ribosomes and followed by glycerol gradient centrifugation. Under these conditions, aurintricarboxylic acid completely inhibits 80S initiation complex formation in the presence of either modified or native STNV. These results suggest that inhibition of in vitro translation of BPDE-modified STNV, in contrast to that of globin mRNA, is not at the level of initiation complex formation but possibly by premature termination of growing polypeptides.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1982

Comparative studies on ribonucleic acid dependent RNA polymerases in cucumber mosaic virus infected cucumber and tobacco and uninfected tobacco plants.

RNA-dependent RNA polymerases have been isolated in almost pure form from cucumber mosaic virus (CMV) infected cucumber cotyledons and from tobacco leaves and were compared with the less pure enzyme from uninfected tobacco. The purified polymerase from cucumber shows on sodium dodecyl sulfate gels two peptide chains of about 100 and 112 kdaltons. The enzyme from tobacco shows a close doublet of about 125 kdaltons, which is also present in the less pure preparation from healthy tobacco. While both the cucumber and tobacco enzymes can use many polynucleotides and RNAs as templates, considerable quantitative differences exist, poly(C) being by far the most effective template for the cucumber enzyme but of low activity with the tobacco enzyme and poly(UG) being highly active with the latter but not the former. Poly(A) and poly(G) are inactive. Different viral RNAs, including CMV RNA, show smaller differences. The sedimentation rates of the enzyme from both sources are the same as that of gamma-globulin. A uridine 5'-triphosphate (UTP) terminal transferase also present in both plants sediments much more slowly and can be completely removed from the RNA polymerases. However, slight nucleolytic activity remains associated with the purified polymerases and appears to be proportional to the polymerase activity. The conclusion derived from these data is that the RNA-dependent RNA polymerases of different plants differ and are not detectably affected by virus infection in qualitative terms while being produced in greatly increased amounts upon some virus infections. Similar conclusions were previously reached with less purified enzyme preparations from tobacco as compared to cowpea, infected with different viruses, if any.

Kinetics↗
PubMed1982

Reconstitution of rods from tobacco mosaic virus protein and RNA modified with bulky carcinogens.

Tobacco mosaic virus (TMV) RNA was treated with radioactive N-acetoxy-2-acetylaminofluorene (N-acetoxy-AAF) and (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BaP diol epoxide) to obtain 3-25 adducts per molecule. Modified full length 30S RNAs and unmodified RNA were reconstituted for various time periods with TMV protein. The particulate products were separated by ultracentrifugation, and the amounts of virus-like material were quantitated by UV spectrophotometry. The length distribution and general appearance of the virus-like rods were studied by electron microscopy. Neither type of carcinogen prevented typical rod formation, but the rate of formation and the maximal yield of reconstituted particles diminished with increasing modification by both agents. The rod length distribution also showed progressively lesser numbers of full-length virus rods. The particulate material contained approximately the same number of adducts as the modified RNA. Thus, it appears that these carcinogen modifications of guanine residues at the N-2 or C-8 atoms did not prevent orderly protein assembly on the RNA but instead slowed up this process and frequently stopped it, possibly at sites where adducts happen to be clustered.

2-Acetylaminofluorene↗