J. Biol. Chem., Vol. 261, Issue 16, 7119-7122, 06, 1986
Preferential binding of DNA primase to the nuclear matrix in HeLa cells
SH Wood and JM Collins
Studies of the spatial organization of DNA replication have provided
increasing evidence of the importance of the nuclear matrix. We have
previously reported a relationship between rates of DNA synthesis and the
differential binding of DNA polymerase alpha to the nuclear matrix over the
S-phase. We now report the detection of DNA primase bound to the HeLa
nuclear matrix. Matrix-bound primase was measured both indirectly, by the
incorporation of [32P]dAMP into an unprimed single- stranded template,
poly(dT), and directly, by the incorporation of [3H]AMP into matrix DNA.
Characteristics of this system include a requirement for ATP, inhibition by
adenosine 5'-O-(thiotriphosphate), a primase inhibitor, and insensitivity
to aphidicolin and alpha- amanitine, inhibitors of polymerase alpha and RNA
polymerase, respectively. Subcellular quantification of primase and
polymerase alpha activity revealed that while most (approximately 72%)
primase activity is bound to the matrix, only a minority (approximately
32%) of polymerase alpha activity is matrix-bound. Treatment of the nuclear
matrix with beta-D-octylglucoside allowed the solubilization of
approximately 54% of primase activity and approximately 39% of the
polymerase alpha activity. This data provides further evidence of a
structural and functional role for the nuclear matrix in DNA replication.
The ability to solubilize matrix-bound replicative enzymes may prove to be
an important tool in the elucidation of the spatial organization of DNA
replication.