Replication Control of IncB and other Plasmids

Funded Activity Summary

Plasmids are extra mini-chromosomes that are present in many bacteria. They carry information that enables their hosts to survive and prosper in hostile environments. Plasmids are able to spread rapidly between bacteria, ensuring that the information they carry is rapidly disseminated throughout bacterial populations. Many plasmids carry information that increases the virulence of their host bacteria, because it adds to their repertoire of toxins and other adjuncts to invasiveness and colonisation, or enables them to survive in the presence of antibiotics. The emergence of multi-drug resistant bacteria and the rapid spread of the ability of bacteria to withstand most antibiotics available to date were mediated by plasmids. Plasmids also carry information that ensures their own survival. The consequence of this is that their bacterial hosts retain the plasmids, even when it is no longer beneficial to do so. For example, plasmids carrying information for resistance to antibiotics are not lost when their bacterial hosts grow in the absence of antibiotics. This is because plasmids have control systems, which ensure that on the one hand, replication of the plasmid keeps pace with the replication of its host, and on the other hand that the plasmid does not produce so many copies of itself that it overwhelms its host. This project examines the intricate regulatory system that a group of antibiotic-resistance plasmids uses to ensure that on average each plasmid molecule is replicated once per bacterial cell cycle. This system uses an antisense RNA, a tertiary RNA structure (pseudoknot) that acts as a translational switch, and a protein that interacts with different sequences on the plasmid to initiate replication. Detailed knowledge of the processes underlying this complex system is required if we are to develop new treatments that will lead to elimination of antibiotic-resistance and virulence-contributing plasmids from populations of pathogenic bacteria.

Funded Activity Details

Start Date: 01-01-2001

End Date: 01-01-2003

Funding Scheme: NHMRC Project Grants

Funding Amount: $347,545.00

Funder: National Health and Medical Research Council

Research Topics

ANZSRC Field of Research (FoR)

Allergy

ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

Antibiotic resistance | Antisense technology | Plasmid-borne virulence genes | Plasmids | RNA pseudoknots | Regulation of translation initiation | Replication control | Replication initiator proteins

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