M. Lebel et al., The Werner syndrome gene product co-purifies with the DNA replication complex and interacts with PCNA and topoisomerase I, J BIOL CHEM, 274(53), 1999, pp. 37795-37799
Werner syndrome (WS) is a recessive disorder characterized by genomic insta
bility and by the premature onset of a number of age-related diseases. To u
nderstand the molecular basis of this disease, we deleted a segment of the
murine Wrn gene and created Wrn-deficient embryonic stem (ES) cells. At the
molecular level, wild type-but not mutant-WS protein co-purifies through a
series of centrifugation, chromatography, and sucrose gradient steps with
the well characterized 17 S multiprotein DNA replication complex. Furthermo
re, wild type WS protein co-immunoprecipitates with a prominent component o
f the multiprotein replication complex, proliferating cell nuclear antigen
(PCNA), In vitro studies also indicate that PCNA binds to a region in the N
terminus portion of the WS protein containing a potential 3'-5' exonucleas
e domain. Finally, human WS protein also co-immunoprecipitates with both PC
NA and topoisomerase I. These results suggest that the WS protein interacts
with several components of the DNA replication fork.