Progressive alteration of telomeric sequences at one end of a yeast linear plasmid and its possible association with reduced plasmid stability.
Mol Genet Genomics
; 266(4): 686-94, 2001 Dec.
Article
in En
| MEDLINE
| ID: mdl-11810241
ABSTRACT
After selection for migration into the nucleus, a cytoplasmic yeast linear plasmid bearing an inverted terminal repeat (ITRs) at each end replicates in Saccharomyces cerevisiae in a linear form, called pTLU, which carries host telomeric repeats (TG(1-3))(n) of about 300-350 bp added to the ITR ends. We previously showed that the nucleotide composition of the added telomeric sequences varied among individual pTLU isolates, while those on the two ends of any given pTLU were always identical. The telomeric sequences of pTLU remained unchanged over numbers of cell generations when cells were selected for expression of the plasmid-borne nuclear marker. We report here that progressive alterations in telomeric sequences can be detected in cells which are grown under non-selective conditions. Surprisingly, in any given molecule, the telomeric alterations occur exclusively on one side, either the left or the right end, while the sequence at the opposite end remained identical to the original, suggesting a difference in the mode of DNA replication between the plasmid ends. These alterations occur over a broad area extending from the termini of telomeres to nucleotides near the junction between the telomeric sequences and the pTLU-ITR, implying that the plasmid ends undergo successive rounds of extension and contraction. Clonal analysis under non-selective conditions indicated that the alterations in telomeric sequences are generally associated with extreme instability of the pTLU plasmid.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Plasmids
/
Saccharomyces cerevisiae
/
DNA, Fungal
/
Telomere
Type of study:
Risk_factors_studies
Language:
En
Journal:
Mol Genet Genomics
Journal subject:
BIOLOGIA MOLECULAR
/
GENETICA
Year:
2001
Type:
Article
Affiliation country:
Japan