Involvement of DNA superhelicity in minichromosome maintenance in Escherichia coli.

摘要: Evidence is presented that Escherichia coli minichromosomes are harbored at superhelical densities which lower than those measured for other E. plasmids but comparable to of the chromosome. When introduced into gyrB decreased-supercoiling mutants, were much more unstable in strains with normal or increased supercoiling properties; fact, certain minichromosome derivatives could not be top mutants. These observations unique minichromosomes, since maintenance did replicate from oriC was altered these Analyses identical sizes different restriction fragment orientations suggested supercoiling-dependent alterations promoter-terminator functions, as well direct effects on replication, may play a role observed instability. Images