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Genetic Properties of a T Factor and T‐ r Recombinants
Author(s) -
Kameda Mitsuo,
Suzuki Mitsue,
Nakajima Takashi,
Harada Kenji,
Mitsuhashi Susumu
Publication year - 1970
Publication title -
japanese journal of microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0021-5139
DOI - 10.1111/j.1348-0421.1970.tb00534.x
Subject(s) - biology , escherichia coli , tetracycline , recombinant dna , microbiology and biotechnology , kanamycin , virology , genetics , antibiotics , gene
Genetic studies have shown that one of the transfer (T) factors, T 95 , carries the following genetic properties: autonomous replication ( rep + ), conjugal transmission ( tra + ), transmission of the host chromosome ( mat + ), inhibition of F‐mating ( ifm + ) or fi + ), inhibition of superinfection with R factor ( irs − ), and suppression of phage proliferation ( spp − ). An Escherichia coli K12 strain carrying T 95 factor is insensitive to male phages (f1 and f2). These facts indicated that the T 95 factor is a sex factor but different from the F factors. By the interaction between T 95 factor and the non‐transferable resistance determinants; r 31 ( tet ) for tetracycline resistance and r 3 ( kan ) for kanamycin resistance, recombinants, T‐ tet , T‐ kan , and T‐ tet‐kan , factors were obtained. These are capable of conferring drug‐resistance and are conjugally transmissible as a single genetic unit. E. coli K12 strains carrying T 95 or T‐ tet factor were insensitive to male phages and T‐ tet (probably T 95 ) factor was transmitted sexually at about 10 −5 transmission frequency after 1 hr of mixed culture. On the contrary, E. coli K12 strains carrying T‐ kan or T‐ tet‐kan factor were found to become sensitive to male phages and their transmission frequency was 10 2 to 10 3 ‐fold higher than that of T‐ tet factor. As a result of these findings, we concluded that the pili formation of T 95 or T‐ tet factor is in a repressed state but the formation of a recombinant between T 95 (or T‐ tet ) and r 3 ( kan ) determinants results in the derepression of pili formation.