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.
Brevibacterium albidum ATCC 15831 에서 유래하여, 재조합 plasmid, pRMG116 에 형질변환된 유전자는 λvir 와 N4 에 대해 내성을 갖게한 반면, φ80, T4, T7 에 대해서는 민감했다. 그러나 대장균의 phage receptor 를 maltose 로 증폭시키면 이들 유전자가 있음에도 불구하고 원래 대장균 처럼 λvir 와 N4 에 대해 민감해졌다.
λ vir DNA 로 대장균을 형질전환시키면 많은 양의 phage가 살아 나왔다.
이상의 결과로부터 pRMG216 에 cloning 된 유전자는 pRMG101 과 마찬가지로 N4 나 λ의 receptor 에 작용하여 phage의 adsorption 을 방해하고, 따라서 phage 에 내성을 주는 것으로 밝혀졌다. phage 에 내성을 주는 균주의 세포막 단백질만을 분리하여 농축시킨 액을 SDS-polyacrylamide gel 에 전기영동 하여 유전자 산물의 분자량을 44,000 과 35,000 dalton 임을 확인했다.
