Complex secondary structure in small Rep_3 plasmids of Acinetobacter spp.

Abstract

AbstractBacterial plasmids are important mobile genetic elements which often carry specific genes important for bacterial successful survival under various inhospitable environmental conditions. Most of the previous research has focused on large plasmids providing these beneficial traits to their host cells. In this study, small cryptic plasmid pALK1 (3 051 bp) was isolated from metallotolerant and alkalitollerant strain Acinetobacter sp. K1. The plasmid encodes Rep_3 family replication protein and MobM mobilization protein but none pALK1-like plasmids were detected in other Acinetobacter strains of environmental and animal origin. The secondary structure of the pALK1 plasmid is characterized by the complexity of multiple sets of direct and inverted repeats in its nucleotide sequence. Comparative genomics was used to hypothesize the biological functions of these repeats in Acinetobacter spp., whereas several similar plasmids with a related organization of direct repeats and palindromes are known in this genus.