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L Breeden

Publications and source records attributed to L Breeden.

22 records · Page 2Linked to original sources
PubMed1981

Mutants of Su+7 tRNA include a functional tRNA with an altered T pseudo uracil CG sequence.

Su+7 tRNA, the amber-suppressing anticodon mutant of tRNA(Trp) (E. coli), also relaxes stringent control. Further mutant Su+7 tRNAs have been isolated that have lost this regulatory effect. The sequence changes we have observed are a unique set. They include partially active suppressor tRNAs with a C to A change in the T pseudo uracil CG common sequence and in the anticodon stem. The activity of the T pseudo uracil CG and anticodon-stem mutants suggests that neither sequence is essential for ribosomal function. The third mutated site, a D-stem alteration, dramatically disturbs tRNA maturation. The mutations add to our knowledge of tRNA function, particularly with regard to the dispensability of the T pseudo uracil CG sequence for activity at the ribosomal A site.

Base Sequence↗
PubMedDate not supplied

Similarity between cell-cycle genes of budding yeast and fission yeast and the Notch gene of Drosophila.

The HO gene of Saccharomyces cerevisiae encodes the endonuclease that initiates mating-type switching. To prevent inopportune switching, HO transcription is restricted to a specific period in the haploid cell cycle, which is just after, and dependent on, the start of the mitotic cell cycle. A repeated promoter element (CACGA4) (refs 7-9) and two trans-acting activators (SWI4 and SWI6) have been identified, which are responsible for the periodic and start-dependent transcription of HO. To understand further the link between start and HO transcription, the SWI6 gene has been cloned and sequenced. The SWI6 protein is similar to the protein in Schizosaccharomyces pombe that is encoded by cdc10 an essential gene specifically required at the start of the cell cycle. The similarity between the SWI6 and cdc10 products, and their common involvement with 'start', suggest that they may share a common mechanism for sensing or executing this critical control step in the cell cycle. The SWI6 and cdc10 proteins also contain two copies of a repeated motif that occurs at least five times in the cytoplasmic domain of the Notch protein of Drosophila melanogaster.

Amino Acid Sequence↗