Origin-defective Mutants of SV40
This extract was created in the absence of an abstract.
Excerpt
In recent years, a great deal has been learned about the way the genome of SV40 is organized and expressed. It is now obvious that the major controlling elements of SV40 are located near map position 0.67. It is here that DNA replication begins (Danna and Nathans 1972; Fareed et al. 1972), that T antigen binds tightly (Tjian 1978), and that the 5′ ends of the early mRNAs map (Reddy et al. 1979). Although the sequence of this region has been determined, little is known about the molecular events during initiation of viral DNA synthesis or about the regulation of early and late transcription. A major obstacle to the analysis of these processes lies in the fact that few mutations exist in this region. The difficulties in obtaining origin-defective mutants are obvious. First, because the target size is small, isolation of such mutants by random mutagenesis of total viral DNA...
