Origin recognition specificity in pT181 plasmids is determined by a functionally asymmetric palindromic DNA element

P. Z. Wang, S. J. Projan, VITALIA BEATRIZ HENRIQUEZ QUEZADA, R. P. Novick

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

The leading strand replication origin of pT181 plasmids consists of two adjacent inverted repeat elements (IR-II and IR-IIl), which are involved in origin recognition by the initiator (Rep) protein. The conserved core element, IR-II, which contains the initiation nick site, is induced by Rep to form a cruciform structure, probably the primary substrate for the initiation of rolling circle replication. The divergent repeat, IR-III, constitutes the determinant of origin recognition specificity. We show here that the distal arm of IR-III is not required for sequence-specific recognition, whereas the proximal arm and central region are required. Since the initiator is dimeric, we presume that it binds symmetrically to IR-III. A unique type of DNA-protein interaction is proposed, in which the lack of sequence requirement for the distal arm is a consequence of binding to the adjacent IR-II, which thereby polarizes the stringency of binding to the two arms of IR-III. In addition, genetic evidence indicates that both the spacing and the phasing of IR-II to IR-III are crucial for function and that the central segment of IR-III may serve to position the two flanking half-sites for optimal interaction of Rep with IR-III.

Original languageEnglish
Pages (from-to)45-52
Number of pages8
JournalEMBO Journal
Volume12
Issue number1
StatePublished - 1 Jan 1993

Keywords

  • DNA replication
  • DNA-binding
  • Plasmid
  • Recognition
  • Staphylococcus aureus

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