Identification Homologous Recombination Function from Haloarchaea Plasmid pHH205

Homologous recombination (HR) was found to be so frequent in haloarchaea that its significance in evolution and diversity of this clade of life might have been underestimated. However, so far there has been no report on recombination function carried on plasmid. Here we report that a 4.8-kb SnaBI-PvuII digested segment from pHH205 might carry such a function. Four constructed plasmids: pUN, pUN-205, pUM and pUM-205, with pUN and pUN205 containing NovR gene, pUM and pUM-205 carrying MevR gene, were used to transform Haloferax volcanii DS52 (radA−). The results showed that only pUN-205 and pUM-205 containing the 4.8-kb SnaBI-PvuII digested segment from pHH205 were able to shift NovR and MevR gene into the chromosome of Haloferax volcanii DS52 through HR, whereas those in pUN and pUM could not, which indicated that the segment from pHH205 does contain a recombination function.