cis-Dominant, transfer-deficient mutants of the Escherichia coli K-12 F sex factor.

AUTOR(ES)

Guyer, M S

RESUMO

Rare conjugational progeny formed by crossing each of five Hfr strains with a recA-F- strain have been characterized. Selection was made for a proximal Hfr marker, taking strict precautions to prevent transfer of recA+ to the zygotes. Most of the progeny were found to be F' strains containing deletion mutant plasmids. With two exceptions, these mutant plasmids have lost all of the tra genes, which are required to confer conjugational donor ability upon a host. In addition, all but the exceptional mutant plasmids were found to be very poorly transmissible from transient heterozygotes which also contain a wild-type F' plasmid. The poor transmissibility is a cis-dominant transfer-defective phenotype which may result from deletion of all or part of the origin of transfer replication (ori), or of a gene determining a cis-acting protein. The two exceptional mutant plasmids may carry short deletions of some of the tra genes or polar tra mutations. The remaining progeny were nonmutant F' strains and F- strains. The frequency with which the F- strains were recovered permits us to estimate that the maximum amount of recombination possible in a recA56 zygote is 10(-6) that of a recA+ zygote.

Documentos Relacionados

• Conjugational Complementation Analysis of Transfer-Deficient Mutants of Flac in Escherichia coli
• Conjugational Complementation Analysis of Transfer-Deficient Mutants of Flac in Escherichia coli
• Beginning a Genetic Analysis of Conjugational Transfer Determined by the F Factor in Escherichia coli by Isolation and Characterization of Transfer-Deficient Mutants
• Five control systems preventing transfer of Escherichia coli K-12 sex factor F.
• Recombination and the Escherichia coli K-12 sex factor F.