Cytoplasmic mRNA isolated from cells infected with SV40 was isolated by passage over oligo(dT)-cellulose columns. This RNA was annealed to SV40 DNA fragments produced by cleavage with EcoRII endonuclease. The RNA resistant to RNase digestion was analyzed by digestion with ribonucleases and oligonucleotide mapping. The results were compared with oligonucleotides from in vitro transcripts of the ...

The HhaI methyltransferase recognizes the sequence GCGC and transfers a methyl group to C5 of the first cytosine residue. All m5C-methyltransferases contain a highly conserved sequence motif called the P-C motif. The cysteine residue of this motif is involved in catalysis by forming a covalent bond with the 6-position of cytosine prior to methyl group transfer. For the EcoRII methyltransferase,...

Extracts from Agrobacterium tumefaciens strain ID135 contain three enzymes that have been characterized and partially purified. The first enzyme, a DNA topoisomerase, appeared to relax only negatively twisted DNA. The second enzyme, Atu I, a type II restriction endonuclease, generated the identical DNA digestion pattern as EcoRII when several DNAs were used. The third enzyme, endonuclease A, sh...