Replication of staphylococcal multiresistance plasmids

Area of Science:

• Molecular Biology
• Microbiology
• Genetics

Background:

• Staphylococcal multiresistance plasmids are categorized into three main groups based on structure and function.
• Understanding the replication mechanisms of these plasmids is crucial for comprehending their persistence and spread.

Purpose of the Study:

• To analyze and compare the replication functions of representative plasmids from the three major staphylococcal multiresistance plasmid groups.
• To investigate the evolutionary relationships and functional roles of replication initiation genes and associated upstream genes.

Main Methods:

• Comparative nucleotide sequence analysis of replication initiation genes (rep) and upstream open reading frames (orfs).
• Construction and functional analysis of minireplicons to assess the role of specific genes in plasmid stability.
• Sequence similarity searches against databases of plasmids from various gram-positive genera.

Main Results:

• Replication initiation genes from pSK1, pSK41, and pI9789::Tn552 are evolutionarily related to each other and to other gram-positive plasmids.
• The pSK1 plasmid's orf245 is essential for its segregational stability, a feature absent in the conjugative pSK41 plasmid.
• Many large multiresistance plasmids in staphylococci share a common, evolutionarily related theta-mode replication system.

Conclusions:

• Despite previous assumptions of unrelatedness, major staphylococcal multiresistance plasmids employ a conserved theta-mode replication strategy.
• The orf245 gene plays a significant role in the stability of certain staphylococcal replicons.
• This conserved replication system likely contributes to the successful dissemination of antibiotic resistance genes in staphylococcal populations.