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B S Dudock

Publications and source records attributed to B S Dudock.

At least 19 recordsLinked to original sources
PubMed1989

The nucleotide sequence and characterization of four chloroplast tRNAs from the alga codium fragile.

The nucleotide sequences of four chloroplast tRNAs (methionine elongator, lysine, glycine, and arginine) from the siphonaceous green alga Codium fragile have been determined. These tRNAs have an unusually high A-U content compared to other chloroplast tRNAs and show varied, but in general only limited, sequence homology to the corresponding tRNAs of other chloroplasts. The locations of the genes for these four tRNAs have been determined and they show no similarity to the location of the corresponding tRNA genes in other chloroplasts. The Codium chloroplast glycine tRNA has an unmodified uridine in the wobble position of the anticodon, a characteristic rarely found in tRNA but present in mitochondrial tRNAs which read the genetic code by extended wobble.

Base Sequence↗
PubMed1989

Unusual characteristics of Codium fragile chloroplast DNA revealed by physical and gene mapping.

A complete physical map of the Codium fragile chloroplast genome was constructed and the locations of a number of chloroplast genes were determined. Several features of this circular genome are unusual. At 89 kb in size, it is the smallest chloroplast genome known. Unlike most chloroplast genomes it lacks any large repeat elements. The 8 kb spacer region between the 16S and 23S rRNA genes is the largest such spacer characterized to date in chloroplast DNA. This spacer region is also unusual in that it contains the rps12 gene or at least a portion thereof. Three regions polymorphic for size are present in the Codium chloroplast genome. The psbA and psbC genes map closely to one of these regions, another region is in the spacer between the 16S and 23S rRNA genes and the third is very close to or possibly within the 16S rRNA gene. The gene order in the Codium genome bears no marked resemblance to either the "consensus" vascular plant order or to that of any green algal or bryophyte genome.

Chloroplasts↗
PubMed1987

A novel variety of 4.5 S RNA from Codium fragile chloroplasts.

An unusual new chloroplast RNA has been isolated and sequenced in the siphonous green alga, Codium fragile. This RNA is 94 nucleotides in length, has an unusually high A + U content (73%), contains no modified residues, and is as abundant as a single chloroplast tRNA species. Although this RNA is 4.5 S in size, it bears little sequence homology to the widely found and highly conserved 4.5 S RNAs present in the chloroplasts of higher plants. Nevertheless, this RNA may indeed by analogous to the higher plant 4.5 S RNAs, since the Codium 4.5 S RNA has the potential to form a secondary structure which in many respects is remarkably similar to that of known chloroplast 4.5 S RNAs, and hybridization data strongly suggests that the 4.5 S RNA is part of the ribosomal RNA operon, as is the case in higher plant chloroplasts.

Base Sequence↗
PubMed1983

The nucleotide sequence of arginine tRNACCG from bovine liver.

The nuclotide sequence of arginine tRNA(CCG) from bovine liver was determined to be: pG-A-C-C-C-A-G-U-m(1)G-m(2)G-C-C-U-A-A-D-Gm-G-A-D-A-A-G-G-C-A-psi-C-A-G-C-Cm-U-C-C-G-m(1)G-A-G-C-U-G-G-G-G-A-D-U-G-psi-G-G-G-T-psi-C-G-m(1)A-G-U-C-C-C-A-U-C-U-G-G-G-U-C-G-C-C-A(OH). This arginine tRNA is 76 nucleotides in length with 13 modified bases and has an anticodon of CCG. The sequence of this molecule is substantially different from those of other arginine tRNAs sequenced to date and is the only arginine tRNA sequenced which would be expected to recognize the codon CGG.Images

Animals↗
PubMed1983

Characterization and nucleotide sequence of a chicken gene encoding an opal suppressor tRNA and its flanking DNA segments.

A naturally occurring opal suppressor serine tRNA has been purified from chicken liver and used as a probe to isolate the corresponding gene from a library of chicken DNA in bacteriophage lambda. This minor tRNA is encoded by a single-copy gene that is not part of a tRNA gene cluster. DNA sequence analysis of the gene and its flanking DNA segments shows that the gene is encoded in an 87-base-pair segment without intervening sequences and specifies a tRNA that reads the termination codon UGA. This gene has additional nucleotides in the 5' internal promoter region but has a normal 3' internal promoter sequence and the usual termination signal.

Animals↗
PubMed1982

The gene for a spinach chloroplast isoleucine tRNA has a methionine anticodon.

The nucleotide sequence of the gene for spinach chloroplast tRNAIle1 has been determined. The gene is found in two copies located in the inverted repeat regions of spinach chloroplast DNA, but not within the ribosomal RNA spacer. Both copies of the tRNAIle1 gene have been sequenced and found to be identical. A very unusual characteristic of the tRNAIle1 gene is that the anticodon is CAT which is a methionine anticodon. In the tRNA the C residue in the anticodon is subsequently modified, presumably to prevent misreading of the genetic code. The spinach chloroplast tRNAIle1 gene is colinear with its RNA sequence and does not contain an intervening sequence as has been reported for maize chloroplast tRNAIle2 (Koch, W., Edwards, K., and Kossel, H. (1981) Cell 25, 203-213). The tRNAIle1 gene does not code for the 3'-terminal CCA end, nor do any other tRNA genes appear to be contiguous with this gene.

Anticodon↗
PubMed1982

Nucleotide sequence of a spinach chloroplast isoleucine tRNA.

The nucleotide sequence of a spinach chloroplast isoleucine tRNA (spinach chloroplast tRNAIle1) has been determined. This tRNA has an unusual structural feature in that it contains an extra non-base paired nucleotide within the double-stranded anticodon stem. Spinach chloroplast tRNAIle1 shows surprisingly little homology to other isoleucine tRNAs. Moreover, the homology it does show is essentially equal for the isoleucine tRNAs from prokaryotes, eukaryotes, and chloroplasts. In addition, this tRNA is as homologous to the methionine elongator tRNAs of Escherichia coli and spinach chloroplasts as it is to other isoleucine tRNAs. Spinach chloroplast tRNA1Ile contains the modified residue N2,N2-dimethylguanosine which is characteristically found in eukaryotic but not in prokaryotic tRNAs.

Base Sequence↗
PubMed1982

Structure of a spinach chloroplast threonine tRNA gene.

The gene for spinach chloroplast tRNAThr3 has been sequenced and is co-linear with the tRNA, does not contain an intervening sequence, and does not code for the 3'-terminal CCA, which is added post-transcriptionally. This gene shares features with prokaryotic, eukaryotic, and mitochondrial tRNA genes. The opposite strand of the tRNA gene contains a proper ribosome binding site, homology to a classical bacterial promoter, and could potentially code for a small peptide.

Base Sequence↗
PubMed1980

Homology between chloroplast and prokaryotic initiator tRNA. Nucleotide sequence of spinach chloroplast methionine initiator tRNA.

The nucleotide sequence of a chloroplast methionine initiator tRNA from spinach has been determined. Although from a eukaryotic organism, this tRNA strongly resembles prokaryotic initiator tRNAs. Spinach chloroplast tRNAMetf has a much higher sequence homology with prokaryotic initiator tRNAs (81 to 84%) than with eukaryotic initiator tRNAs (64 to 69%). In addition, it possesses the two unique features of prokaryotic initiator tRNAs, lacking a base pair between the 5'-terminal residue and the fifth nucleotide from the 3'-end and containing a T-psi-C-A sequence in loop IV. Also, like prokaryotic initiator tRNAs, the chloroplast tRNAMetf is 77 nucleotides long and has few modified nucleosides (2'-O-methylguanosine, dihydrouridine, 7-methylguanosine, ribothymidine, and pseudouridine). This chloroplast initiator tRNA is strikingly different in sequence homology (55 to 62%), number of residues, and structure from mitochondrial initiator tRNAs. Restriction enzyme mapping techniques have shown that the chloroplast tRNAMEtf hybridizes to spinach chloroplast DNA. A set of characteristic chloroplast tRNA features seems to be emerging from a comparison of this tRNAMetf and several other chloroplast tRNAs which have been completely or partially sequenced. All have a 2'-O-methylated G-G sequence in the dihydrouridine loop, and the sequence T-psi-C-A, as opposed to T-psi-C-G, is predominantly found in loop IV. This is the reverse of the situation encountered in the overall non-chloroplast tRNA population.

Base Sequence↗
PubMed1980

Nucleotide sequence of a spinach chloroplast threonine tRNA.

The nucleotide sequence of a spinach chloroplast threonine tRNA has been determined. This chloroplast threonine tRNA has been determined. This chloroplast threonine tRNA has 75 nucleotides, which is the same chain length as the recently determined threonine tRNA from yeast mitochondria. This contrasts with the 6 non-organelle threonine tRNAs sequenced to date, which are 76 nucleotides in length. However, other than this similarity in size, the chloropast tRNAThr has little similarlity to the yeast mitochondrial threonine tRNA, and shows essentially equal homology to both prokaryotic and eukaryotic feature of sequence homology to other threonine tRNAs, there is a 19-nucleotide segment encompassing the entire T psi C stem and loop region, that, except for post-transcriptional modifications, is identical in this spinach chloroplast tRNAThr and in yeast cytoplasmic tRNAThr1A. A most unusual feature of this spinach chloroplast tRNAThr is that it has an A residue at the 5'-end of the anticodon loop, a site that is occupied by a pyrimidine in all other tRNAs sequenced to date. Other than this feature, the tRNAThr contains all of the invariant and semi-invariant residues normally found in tRNAs. This tRNA hybridizes to spinach chloroplast DNA, but does not hybridize to the same region of the spinach chloroplast genome that contains the genes for spinach chloroplast tRNA1Thr or tRNA2Thr. This tRNA therefore appears to be a third isoaccepting species of threonine tRNA encoded by spinach chloroplast DNA.

Base Sequence↗
PubMed1977

Complete nucleotide sequence and properties of the major species of glycine transfer RNA from wheat germ.

The complete nucleotide sequence of wheat germ tRNA1Gly has been determined. It is a small tRNA, containing only 74 nucleotides of which 10 are methylated or otherwise modified. Several important features of this tRNA are: (a) a complete absence of ribothymidine which is the most common methylated nucleoside in tRNA; (b) a methylated sugar in the acceptor stem which is a region almost always free of modified residues; and (c) unusually weak base pairing in the dihydrouridine stem region consisting of only one standard A-U base pair in addition to G pi, AC, and GU. This tRNA functions in a wheat germ cell free protein synthesizing system directed by either natural mRNAs or poly(G,U). The complete nucleotide sequence of wheat germ tRNAlGly is: pG-C-A-Cm-CAGU-m1G-G-U-C-PSI-A-G-D-G-G-U-A-A-U-A-G-U-A-C-C-C-U-G-C-C-A-mC-G-G-U-A-C-A-C-A-G-A-mC-m5C-G-G-G-U-PSI-C-G-mA-U-U-C-C-C-G-G-C-U-G-G-U-G-C-A-C-C-AOH.

Base Sequence↗