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H Grosjean

Publications and source records attributed to H Grosjean.

At least 19 recordsLinked to original sources
PubMed1992

Identity elements for N2-dimethylation of guanosine-26 in yeast tRNAs.

N2,N2-dimethylguanosine (m2(2)G) is a characteristic nucleoside that is found in the bend between the dihydro-uridine (D) stem and the anticodon (AC) stem in over 80% of the eukaryotic tRNA species having guanosine at position 26 (G26). However, since a few eukaryotic tRNAs have an unmodified G in that position, G26 is a necessary but not a sufficient condition for dimethylation. In yeast tRNA(Asp) G26 is unmodified. We have successively changed the near surroundings of G26 in this tRNA until G26 became modified to m2(2)G by a tRNA(m2(2)G26)methyltransferase in Xenopus laevis oocytes. In this way we have identified the two D-stem basepairs C11-G24, G10-C25 immediately preceding G26 as major identity elements for the dimethylating enzyme modifying G26. Furthermore, increasing the extra loop in tRNA(Asp) from four to the more usual five bases influenced the global structure of the tRNA such that the m2(2)G26 formation was drastically decreased even if the near region of G26 had the two consensus basepairs. We conclude that not only are the two consensus base pairs in the D-stem a prerequisite for G26 modification, but also is any part of the tRNA molecule that influence the 3D-structure important for the recognition between nuclear coded tRNAs and the tRNA(m2(2)G26)methyltransferase.

Animals↗
PubMed1979

On codon usage.

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Codon↗
PubMed1979

Evolution of methionine initiator and phenylalanine transfer RNAs.

Sequence data from methionine initiator and phenylalanine transfer RNAs were used to construct phylogenetic trees by the maximum parsimony method. Although eukaryotes, prokaryotes and chloroplasts appear related to a common ancestor, no firm conclusion can be drawn at this time about mitochondrial-coded transfer RNAs. tRNA evolution is not appropriately described by random hit models, since the various regions of the molecule differ sharply in their mutational fixation rates. "Hot" mutational spots are identified in the Tpsic, the amino acceptor and the upper anticodon stems; the D arm and the loop areas on the other hand are highly conserved. Crucial tertiary interactions are thus essentially preserved while most of the double helical domain undergoes base pair interchange. Transitions are about half as costly as transversions, suggesting that base pair interchanges proceed mostly through G-U and A-C intermediates. There is a preponderance of replacements starting from G and C but this bias appears to follow the high G + C content of the easily mutated base paired regions.

Animals↗
PubMed1978

Bacteriophage MS2 RNA: a correlation between the stability of the codon: anticodon interaction and the choice of code words.

The non-random distribution of degenerate code words in Bacteriophage MS2 RNA can be explained partially by considerations of the stability of the codon-anticodon complex in prokaryotic systems. Supporting this hypothesis we note that wobble codons are positively selected in codons having G and/or C in the first two positions. In contrast, wobble codons are statistically less likely in codons composed of A and U in the first two positions. Analyses of nucleotides adjacent to 5' and 3' ends of codons indicate a nonrandom distribution as well. It is thus likely that some elements of RNA evolution are independent of the structural needs of the RNA itself and of the translated protein product.

Anticodon↗
PubMed1975

A method for the isolation of specific tRNA precursors.

tRNA affinity chromatography, based on complex formation between tRNAs with complementary anticodons, has been applied to the isolation of specific tRNA precursors. When [32P]RNA, isolated from an Escherichia coli strain containing a thermolabile ribonuclease P, was chromatographed on resin-bound yeast phenylalanine tRNA, precursor tRNAGlu (possessing the complementary anticodon) was specifically retained. Likewise, precursor tRNAPhe was isolated from a column of resin-bound E. coli glutamate tRNA. Both precursor tRNAs isolated were monomeric and may be processed products of an originally larger RNA precursor. Both tRNA precursors contain additional nucleotides beyond the 5'-end of the mature tRNA and have all modified bases found in mature tRNA. The method can be extended to isolate other tRNA precursors by affinity chromatography with different tRNAs. Since the principle of complementary anticodon interaction is not restricted to any particular organism, specific precursor tRNAs from other sources may also be isolated in this way.

Base Sequence↗