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W E Barnett

Publications and source records attributed to W E Barnett.

At least 19 recordsLinked to original sources
PubMed1982

The nucleotide sequence of blue-green algae phenylalanine-tRNA and the evolutionary origin of chloroplasts.

Phenylalanine tRNA from the blue-green alga, Agmenellum quadruplicatum, has been purified to homogeneity. The nucleotide sequence of this tRNA was determined to be: (see tests) Comparisons of the sequence and the modified nucleosides of this tRNA with those of other tRNAPhes thus far sequenced, indicate that this blue green algal tRNAPhe is typically prokaryotic and closely resembles the chloroplast tRNAPhes of higher plants and Euglena. The significance of this observation to the evolutionary origin of chloroplasts is discussed.

Base Sequence↗
PubMed1981

The nucleotide sequence of Euglena cytoplasmic phenylalanine transfer RNA. Evidence for possible classifications of Euglena among the animal rather than the plant kingdom.

The nucleotide sequence of cytoplasmic phenylalanine tRNA from Euglena gracilis has been elucidated using procedures described previously for the corresponding chloroplastic tRNA [Cell, 9, 717 (1976)]. The sequence is: pG-C-C-G-A-C-U-U-A-m(2)G-C-U-Cm-A-G-D-D-G-G-G-A-G-A-G-C-m(2)2G-psi-psi-A-G-A-Cm -U-Gm-A-A-Y-A-psi-C-U-A-A-A-G-m(7)G-U-C-*C-C-U-G-G-T-psi-C-G-m(1)A-U-C-C-C-G-G- G-A-G-psi-C-G-G-C-A-C-C-A. Like other tRNA Phes thus far sequenced, this tRNA has a chain length of 76 nucleotides. The sequence of E. gracilis cytoplasmic tRNA Phe is quite different (27 nucleotides out of 76 different) from that of the corresponding chloroplastic tRNA but is surprisingly similar (72 out of 76 nucleotides identical) to that of tRNA Phe from mammalian cytoplasm. This extent of sequence homology even exceeds that found between E. gracilis and wheat germ cytoplasmic tRNA Phe. These findings raise interesting questions on the evolution of tRNAs and the taxonomy of Euglena.

Animals↗
PubMed1980

The nucleotide sequence of phenylalanine tRNA from the cytoplasm of Neurospora crassa.

The phenylalanine tRNA from the cytoplasm of Neurospora crassa has been purified and sequenced. The sequence is: pGCGGGUUUAm2GCUCA (N) GDDGGGAGAGCm22GpsiCAGACmUGmAAYApsim5CUGAAGm7GDm5CGUGUGTpsiCGm1AUCCACACAAACCGCACCAOH. Both in the nature of modified nucleotides which are present in this tRNA and in the overall sequence, this tRNA resembles more closely phenylalanine tRNAs of eukaryotic cytoplasm than those of prokaryotes. The sequence of this tRNA differs from those of the corresponding tRNAs of wheat germ and yeast by only 6 and 7 nucleotides respectively out of 76 nucleotides.U

Base Sequence↗
PubMed1977

Cloned ribosomal RNA genes from chloroplasts of Euglena gracilis.

Fragments of Euglena chloroplast DNA generated by endonuclease R-Eco RI were separated by agarose-gel electrophoresis into 24 distinct bands. At least five fragments contain sequences complementary to chloroplast ribosomal RNA, Most of the Eco RI fragments have been cloned in a plasmid of Escherichia coli. Three of the cloned fragments were shown to contain chloroplast ribosomal RNA sequences by DNA-RNA hybridization.

Chloroplasts↗
PubMed1977

Nucleotide sequence of Neurospora crassa cytoplasmic initiator tRNA.

Initiator methionine tRNA from the cytoplasm of Neurospora crassa has been purified and sequenced. The sequence is: pAGCUGCAUm1GGCGCAGCGGAAGCGCM22GCY*GGGCUCAUt6AACCCGGAGm7GU (or D) - CACUCGAUCGm1AAACGAG*UUGCAGCUACCAOH. Similar to initiator tRNAs from the cytoplasm of other eukaryotes, this tRNA also contains the sequence -AUCG- instead of the usual -TphiCG (or A)- found in loop IV of other tRNAs. The sequence of the N. crassa cytoplasmic initiator tRNA is quite different from that of the corresponding mitochondrial initiator tRNA. Comparison of the sequence of N. crassa cytoplasmic initiator tRNA to those of yeast, wheat germ and vertebrate cytoplasmic initiator tRNA indicates that the sequences of the two fungal tRNAs are no more similar to each other than they are to those of other initiator tRNAs.

Amino Acyl-tRNA Synthetases↗
PubMed1976

The first nucleotide sequence of an organelle transfer RNA: chloroplastic tRNAphe.

The primary sequence of phenylalanine tRNA (tRNAphe) from the chloroplasts of Euglena gracilis has been determined: pG-C-U-G-G-G-A-U-A-G-C-U-C-A-G-D-U-G-Gm-U(U)-A-G-A-G-C-G-G-A-G-G-A-C-U-G-A-A-A-A-PSI-C-C-U-U-G-U-m7G-Py-C-A-C-C-A-G-T-psi-C-A-A-A-U-C-U-G-G-U-U-C-C-U-A-G-C-A-C-C-A. This represents the first nucleotide sequence determined for an organelle tRNA. As do all other tRNAPhes thus far sequenced, chloroplastic tRNAPhe contains 76 nucleotides. Both in the nature of its modified nucleotides and in its sequence (although the sequence of all known tRNAPhes is quite similar), chloroplastic tRNAPhe more closely resembles procaryotic tRNAPhes than it resembles those from the cytoplasm of eucaryotes. There are eight positions in the tRNAPhe molecule where nucleotides are invariant in procaryotes but differ from invariant nucleotides in eucaryotes; at five of these positions, chloroplastic tRNAPhe is similar to procaryotes. The possible evolutionary significance of this intermediate type of structure is discussed.

Base Sequence↗
PubMed1976

Transcriptional origin of Euglena chloroplast tRNAs.

tRNA.DNA hybridization studies indicate that Euglena chloroplast tRNAs are transcriptional products of the chloroplast genome, which contains approximately 26 tRNA cistrons. Hybridization with purified chloroplast tRNA(Phe) and tRNA(Asp) shows that the chloroplast genome contains one cistron for each of these two species. No hybridization of chloroplast tRNA with nuclear DNA was observed. tRNAs from Euglena cytoplasm, Escherichia coli, and Agmenellum quadraduplicatum do not compete with chloroplast tRNA for hybridization with chloroplast DNA. Evidence is presented that photoinduction of chloroplast tRNAs is at the level of transcription rather than maturation of tRNA precursor molecules.

Journal Article↗
PubMed1974

The sites of transcription and translation for Euglena chloroplastic aminoacyl-tRNA synthetases.

We find that cycloheximide completely blocks the light-induced apearance of Euglena chloroplastic aminoacyl-tRNA synthetases in dark-grown cells of Euglena gracilis var. bacillaris. Streptomycin, on the other hand, has no effect on the light-induction of these organellar enzymes. These observations, together with the finding that an aplastidic mutant (strain W(3)BUL, which has neither significant plastid structure nor detectable chloroplast DNA) contains low levels of the chloroplastic synthetases, indicate that the chloroplastic synthetases are transcriptional products of nuclear genes and are translated on cytoplasmic ribosomes prior to compartmentalization within the chloroplasts.

Amino Acyl-tRNA Synthetases↗
PubMed1973

A Cytoplasmic Regulatory Mutant of Euglena: Constitutivity for the Light-Inducible Chloroplast Transfer RNAs.

An ultraviolet-induced cytoplasmic mutant (G(1)BU) of Euglena gracilis Klebs var. bacillaris Pringsheim is described. G(1)BU, in addition to being golden in color and containing smaller amounts of chlorophyll than wild type when grown in the light, is a regulatory constitutive mutant for the light-inducible chloroplast isoleucine and methionine tRNAs; i.e., these two tRNAs are present in dark-grown G(1)BU cells at approximately the levels present in light-grown wild-type cells. Six other mutants were also examined for normal control of plastid tRNA biosynthesis; all four of the aplastidic mutants (lacking appreciable plastid structures and detectable plastid DNA) are incapable of chloroplast tRNA biosynthesis, whereas two other color mutants that do contain plastids and chloroplast DNA have normal plastid tRNA regulation.

Journal Article↗