Genes, which make their host resistant to lambda, were isolated from Brevibacterium albidum ATCC15831 and introduced into Escherichia coli HB101. The clones transformed by the recombinant plasmid, pRMG216, were totally resistant to virulent lambda and N4, but sensitive to 080, T4, and T7.
There were no type II restriction activities found in the extracts of E. coli HB101 (pRMG216) which were fractionated by heparin-agarose column chromatography(8). While the two modification activities was detected from the extract, lambda DNA methylated by these modification enzyme were completely digested by each one of the endonuclease, Ban I, BamH I(8).
When phage DNAs were transfected into the clone carrying not only Φ80 but also N4 and lambda DNA were propagated in the resistant clones.
E. coli C600(pRMG116) grew faster than E. coli C600(pBR322) at the first time but, soon after grew slower in minimal medium containing glucose or maltose. Furthermore, even E. coli K-12(pRMG216) became sensitive to N4 and lambda when the maltose transport system was induced by maltose.
The products of the genes in pRMG116 were shown by SDS-PAGE of membrane protein-enriched extract of the clone. The molecular weights of the proteins as measured were about 35,000 and 44,000 daltons.