The RNA-splicing factor PSF/p54(nrb) controls DNA-topoisomerase I activity by a direct interaction
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The RNA-splicing factor PSF/p54(nrb) controls DNA-topoisomerase I activity by a direct interaction. / Straub, Tobias; Grue, Pernille; Uhse, Anette; Lisby, Michael; Knudsen, Birgitta R.; Tange, Thomas; Westergaard, Ole; Boege, Fritz.
I: Journal of Biological Chemistry, Bind 273, Nr. 41, 09.10.1998, s. 26261-26264.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - The RNA-splicing factor PSF/p54(nrb) controls DNA-topoisomerase I activity by a direct interaction
AU - Straub, Tobias
AU - Grue, Pernille
AU - Uhse, Anette
AU - Lisby, Michael
AU - Knudsen, Birgitta R.
AU - Tange, Thomas
AU - Westergaard, Ole
AU - Boege, Fritz
PY - 1998/10/9
Y1 - 1998/10/9
N2 - DNA-topoisomerase I has been implied in RNA splicing because it catalyzes RNA strand transfer and activates serine/arginine-rich RNA-splicing factors by phosphorylation. Here, we demonstrate a direct interaction between topoisomerase I and pyrimidine tract binding protein-associated splicing factor (PSF), a cofactor of RNA splicing, which forms heterodimers with its smaller homolog, the nuclear RNA-binding protein of 54 kDa (p54(nrb)). Topoisomerase I, PSF, and p54(nrb) copurifled in a 1:1:1 ratio from human A431 cell nuclear extracts. Specific binding of topoisomerase I to PSF (but not p54(nrb)) was demonstrated by coimmunoprecipitation and by far Western blotting, in which renatured blots were probed with biotinylated topoisomerase I. Chemical cross-linking of pure topoisomerase I revealed monomeric, dimeric, and trimeric enzyme forms, whereas in the presence of PSF/p54(nrb) the enzyme was cross-linked into complexes larger than homotrimers. When topoisomerase I was complexed with PSF/p54(nrb) it was 16- fold more active than the pure enzyme, which could be stimulated 5- and 16- fold by the addition of recombinant PSF or native PSF/p54(nrb), respectively. A physiological role of this stimulatory mechanism seems feasible, because topoisomerase I and PSF showed a patched colocalization in A431 cell nuclei, which varied with cell cycle.
AB - DNA-topoisomerase I has been implied in RNA splicing because it catalyzes RNA strand transfer and activates serine/arginine-rich RNA-splicing factors by phosphorylation. Here, we demonstrate a direct interaction between topoisomerase I and pyrimidine tract binding protein-associated splicing factor (PSF), a cofactor of RNA splicing, which forms heterodimers with its smaller homolog, the nuclear RNA-binding protein of 54 kDa (p54(nrb)). Topoisomerase I, PSF, and p54(nrb) copurifled in a 1:1:1 ratio from human A431 cell nuclear extracts. Specific binding of topoisomerase I to PSF (but not p54(nrb)) was demonstrated by coimmunoprecipitation and by far Western blotting, in which renatured blots were probed with biotinylated topoisomerase I. Chemical cross-linking of pure topoisomerase I revealed monomeric, dimeric, and trimeric enzyme forms, whereas in the presence of PSF/p54(nrb) the enzyme was cross-linked into complexes larger than homotrimers. When topoisomerase I was complexed with PSF/p54(nrb) it was 16- fold more active than the pure enzyme, which could be stimulated 5- and 16- fold by the addition of recombinant PSF or native PSF/p54(nrb), respectively. A physiological role of this stimulatory mechanism seems feasible, because topoisomerase I and PSF showed a patched colocalization in A431 cell nuclei, which varied with cell cycle.
UR - http://www.scopus.com/inward/record.url?scp=0032500516&partnerID=8YFLogxK
U2 - 10.1074/jbc.273.41.26261
DO - 10.1074/jbc.273.41.26261
M3 - Journal article
C2 - 9756848
AN - SCOPUS:0032500516
VL - 273
SP - 26261
EP - 26264
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 41
ER -
ID: 241305907