Translesion DNA polymerases are required for spontaneous deletion formation in Salmonella typhimurium.
Proc Natl Acad Sci U S A
; 106(25): 10248-53, 2009 Jun 23.
Article
en En
| MEDLINE
| ID: mdl-19525399
ABSTRACT
How spontaneous deletions form in bacteria is still a partly unresolved problem. Here, we show that deletion formation in Salmonella typhimurium requires the presence of functional translesion polymerases. First, in wild-type bacteria, removal of the known translesion DNA polymerases, PolII (polB), PolIV (dinB), PolV (umuDC), and SamAB (samAB), resulted in a 10-fold decrease in the deletion rate, indicating that 90% of all spontaneous deletions require these polymerases for their formation. Second, overexpression of these polymerases by derepression of the DNA damage-inducible LexA regulon caused a 25-fold increase in deletion rate that depended on the presence of functional translesion polymerases. Third, overexpression of the polymerases PolII and PolIV from a plasmid increased the deletion rate 12- to 30-fold, respectively. Last, in a recBC(-) mutant where dsDNA ends are stabilized due to the lack of the end-processing nuclease RecBC, the deletion rate was increased 20-fold. This increase depended on the translesion polymerases. In lexA(def) mutant cells with constitutive SOS expression, a 10-fold increase in DNA breaks was observed. Inactivation of all 4 translesion polymerases in the lexA(def) mutant reduced the deletion rate 250-fold without any concomitant reduction in the amount of DNA breaks. Mutational inactivation of 3 endonucleases under LexA control reduced the number of DNA breaks to the wild-type level in a lexA(def) mutant with a concomitant 50-fold reduction in deletion rate. These findings suggest that the translesion polymerases are not involved in forming the DNA breaks, but that they require them to stimulate deletion formation.
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Bases de datos:
MEDLINE
Asunto principal:
Salmonella typhimurium
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Eliminación de Secuencia
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ADN Polimerasa Dirigida por ADN
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Reparación del ADN
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Roturas del ADN
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2009
Tipo del documento:
Article
País de afiliación:
Suecia