Disease relevance of tus

• tus, the trans-acting gene required for termination of DNA replication in Escherichia coli, encodes a DNA-binding protein [1].
• Although tus mutants exhibit no growth phenotype in laboratory conditions, Salmonella typhimurium and E. coli have nevertheless maintained similar termination systems [2].
• Polar arrest of the simian virus 40 tumor antigen-mediated replication fork movement in vitro by the tus protein-terB complex of Escherichia coli [3].
• In addition to the site-directed mutagenesis studies, the tus genes of Salmonella, Klebsiella, and Yersinia were sequenced and the proteins expressed in E. coli to assess their ability to arrest DNA replication [4].

High impact information on tus

• Insertion of a kanamycin-resistance gene in this open reading frame abolished tus activity [1].
• We also demonstrated that crude extracts of tus+ cells contain a protein which binds to the T2 terminator sequence [1].
• Mutations in the tus gene of Escherichia coli, which encodes the replication arrest protein Tus, were isolated using a selection scheme based on the plasmid pHV750T2+, which transforms tus mutants at a much higher frequency than wild type strains [5].
• Resistance to tus expression mapped to a mutation in the stop codon of the topA gene (topA869), generating an elongated topoisomerase I protein with a marked reduction in activity [6].
• The inverted Ter sites (designated InvTer::spcr) were initially inserted into the chromosome of a delta tus strain to allow unrestrained chromosomal replication [7].

Biological context of tus

• The tus gene encodes a DNA-binding protein (Tus) that inhibits replication forks at specific block-sites within the terminus region of the Escherichia coli chromosome [8].
• In vivo characterization of tus gene expression in Escherichia coli [8].
• Using primer extension and a promoter fusion to characterize in vivo expression, we have demonstrated that the tus transcription start site is within TerB, and that Tus protein autoregulates expression at this weak promoter [8].
• The tus gene of Escherichia coli: autoregulation, analysis of flanking sequences and identification of a complementary system in Salmonella typhimurium [2].
• Although later studies have suggested that fork encounter during termination is an active process involving specific termination sites and the tus protein, the coupling mechanism between termination and cell division remains to be elucidated [9].

Associations of tus with chemical compounds

• Proline pipe helix: structure of the tus proline repeat determined by 1H NMR [10].

Analytical, diagnostic and therapeutic context of tus

• Plasmid DNA was isolated from the tus strain carrying plasmid pOU47 and from a wild-type strain carrying pOU47 in which the right Ter site had been inactivated; in both cases, electron microscopy revealed the presence of multimers as well as rolling-circle structures with double-stranded tails [11].

References