Termination of DNA replication in Escherichia coli requires a trans-acting factor.

AUTOR(ES)

Hill, T M

RESUMO

The terminus region of the Escherichia coli chromosome contains two sites that inhibit the progression of DNA replication forks. These termination sites, designated T1 and T2, are separated by 7.5 min (350 kilobases [kb]) on the genetic map and are located at the extremities of the terminus region. They demonstrate polarity (they stop replication forks traveling in one direction but not the other) and inhibit replication forks that have passed through and are about to leave the terminus. We have used deletion mutations in the terminus region to map the locations of T1 and T2 more accurately and to initiate studies on the mechanism of replication fork inhibition. We have narrowed the boundaries of T1 and T2 to 20 and 4 kb, respectively. T1 maps between kb 80 and 100 on the physical map of the terminus region (J. P. Bouché, J. Mol. Biol. 154:1-20, 1982), and T2 maps between kb 438 and 442. In addition, we report here that deletion of the region containing the T2 termination site inactivated T1. Supplying the T2 region on a plasmid restored T1 function, demonstrating that inhibition of replication at T1 requires a trans-acting factor which maps in the vicinity of termination site T2. We have called this newly identified terminus function the termination utilization substance (tus).

Documentos Relacionados

• tus, the trans-acting gene required for termination of DNA replication in Escherichia coli, encodes a DNA-binding protein.
• The extrachromosomal replication of Dictyostelium plasmid Ddp2 requires a cis-acting element and a plasmid-encoded trans-acting factor.
• Regulated expression of mammalian histone H4 genes in vivo requires a trans-acting transcription factor.
• Transcriptional regulation by triiodothyronine requires synergistic action of the thyroid receptor with another trans-acting factor.
• The bat gene of Halobacterium halobium encodes a trans-acting oxygen inducibility factor.