Antibiotic resistance among some pathogenic microorganisms is frequently related to some genes present in plasmids –DNA molecules capable of replicate independently of the rest of the genome–. Protein ω2 regulates copy number and distribution of these plasmids and, therefore, indirectly influences the acquisition of resistance to antibiotics.
Now, a study published at Nucleic Acids Research by scientists from the Centro Nacional de Biotecnología (CNB-CSIC) reveals the mechanism utilised by ω2 to regulate the expression of genes present in the plasmid and to modulate the resistance to antibiotics.
To fulfil this, ω2 recruit the RNA-polymerase –a key element for gene expression– and promotes its binding union to the correspondent promoter –starting point for DNA transcription–. However, initiation of the transcription is induced only when a limited number of ω2 are bound to the promoter. When the promoter is totally saturated by the presence of ω2, it makes the opposite effect, that is, represses the expression of the genes controlled by this system.
“Stimulation and inhibition of transcription is the mechanism used by ω2 to control the copy number, efficient distribution and survival of the plasmid” explains Juan Carlos Alonso, one of the authors and researcher at the CNB. “Using these mechanisms, ω2 indirectly influences the acquisition of antibiotic resistance genes” concludes the scientist.
- Andrea Volante, Begoña Carrasco, Mariangela Tabone and Juan C. Alonso. The interaction of ω2 with the RNA polymerase β’ subunit functions as an activation to repression switch. Nucleic Acids Research, doi: 10.1093/nar/gkv788