Identification of cis- and trans-acting elements in pHW126, a representative of a novel group of rolling circle plasmids

Wilfried Rozhon, Mamoona Khan, Elena Petutschnig, Brigitte Poppenberger

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


pHW126, pIGRK, pIGMS31 and pRAO1 are the only known members of a novel and as yet uncharacterised family of rolling circle plasmids. pHW126 contains only two open reading frames, of which one shows homology to pMV158-family mobilisation proteins. Here we provide evidence that the second open reading frame encodes a replication protein (Rep). Mutation or deletion of this gene resulted in replication deficient constructs, but providing functional Rep from a compatible vector rescued these constructs, indicating that Rep acts in trans. An approximately 300 bp cis-acting region representing the origin of replication was identified upstream of the rep gene. The origin was identified to be composed of three parts: an accessory region, a conserved stretch and four perfect tandem repeats. The two latter elements were essential for replication. Constructs with a deletion of the accessory region could still replicate, but their loss rate was high, indicating that the accessory region is necessary for plasmid maintenance under non-selective conditions. Interestingly, pHW126 could replicate in all Enterobacteriaceae tested while Agrobacterium tumefaciens and Pseudomonas syringae were inappropriate hosts. Thus, pHW126 seems to have a rather limited host range.

Original languageEnglish
Pages (from-to)70-76
Number of pages7
Issue number1
StatePublished - Jan 2011
Externally publishedYes


  • Enterobacteria
  • Origin of replication
  • Rahnella
  • Replication protein
  • Rolling circle plasmid


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