Telomeric circles are abundant in the stn1-M1 mutant that maintains its telomeres through recombination.
Nucleic Acids Res
; 38(1): 182-9, 2010 Jan.
Article
em En
| MEDLINE
| ID: mdl-19858100
ABSTRACT
Some human cancers maintain their telomeres using the alternative lengthening of telomeres (ALT) mechanism; a process thought to involve recombination. Different types of recombinational telomere elongation pathways have been identified in yeasts. In senescing yeast telomerase deletion (ter1-Delta) mutants with very short telomeres, it has been hypothesized that copying a tiny telomeric circle (t-circle) by a rolling circle mechanism is the key event in telomere elongation. In other cases more closely resembling ALT cells, such as the stn1-M1 mutant of Kluyveromyces lactis, the telomeres appear to be continuously unstable and routinely reach very large sizes. By employing two-dimensional gel electrophoresis and electron microscopy, we show that stn1-M1 cells contain abundant double stranded t-circles ranging from approximately 100 to 30,000 bp in size. We also observed small single-stranded t-circles, specifically composed of the G-rich telomeric strand and tailed circles resembling rolling circle replication intermediates. The t-circles most likely arose from recombination events that also resulted in telomere truncations. The findings strengthen the possibility that t-circles contribute to telomere maintenance in stn1-M1 and ALT cells.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Recombinação Genética
/
DNA Circular
/
Telômero
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Nucleic Acids Res
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Estados Unidos