Replication of nuclear
DNA in eukaryotes presents a tremendous challenge, not only due to the size and complexity of the genome, but also because of the time constraint imposed by a limited duration of S phase during which the entire genome has to be duplicated accurately and only once per cell division cycle. A challenge of this magnitude can only be met by the close coupling of
DNA precursor synthesis to replication. Prokaryotic systems provide evidence for multienzyme and
multiprotein complexes involved in
DNA precursor synthesis and DNA replication. In addition, fractionation of
nuclear proteins from proliferating mammalian cells shows co-sedimentation of
enzymes involved in DNA replication with those required for synthesis of deoxynucleoside triphosphates (dNTPs). Such complexes can be isolated only from cells that are in S phase, but not from cells in G(0)/G(1) phases of cell cycle. The kinetics of deoxynucleotide metabolism supporting DNA replication in intact and permeabilized cells reveals close coupling and allosteric interaction between the
enzymes of dNTP synthesis and DNA replication. These interactions contribute to channeling and compartmentation of deoxynucleotides in the microvicinity of DNA replication. A multienzyme and multiprotein megacomplex with these unique properties is called "
replitase." In this article, we summarize some of the relevant evidence to date that supports the concept of
replitase in mammalian cells, which originated from the observations in Dr. Pardee's laboratory. In addition, we show that
androgen receptor (AR), which plays a critical role in proliferation and viability of
prostate cancer cells, is associated with
replitase, and that identification of constituents of
replitase in
androgen-dependent versus
androgen-independent
prostate cancer cells may provide insights into
androgen-regulated events that control proliferation of
prostate cancer cells and potentially offer an effective strategy for the treatment of
prostate cancer.