The upsurge of antibiotic resistance in pathogenic bacteria is one of the major global health concerns [1]. To address this problem, new antibacterial strategies are required. In this direction, we have recently identified the bacterial signal recognition particle (SRP) pathway as a potential antibacterial target [2]. Bacterial SRP mediates the co-translational transport of nascent proteins to the plasma membrane, and is essential for bacterial cell survival [3-4]. Our approach aimed to inhibit an important RNA-protein interaction to disrupt the functional SRP cycle in bacteria. Antisense peptide nucleic acids (PNAs) were designed to target the bacterial 4.5S RNA-Ffh protein interaction (which makes a functional SRP complex). In vitro studies confirmed that the designed PNAs bound specifically to the target RNA, and inhibited the RNA-protein interaction in a dose-dependent manner, leading to the inhibition of SRP mediated GTP hydrolysis. In vivo studies showed that the cell permeable peptide conjugated PNA effectively inhibited E. coli AS19 bacterial cell growth in a dose-dependent manner. PNA mediated bacterial cell growth inhibition was rescued by over-expression of 4.5S RNA. This study confirms the cellular target of the designed PNA, and validates SRP as a potential system for antibacterial therapeutics. Further, we explored the molecular details of the interaction between designed PNAs and RNA through various biophysical techniques [5]. One of the designed PNAs has a homo-pyrimidine sequence, capable of forming triplexes with homo-purine RNA. The other PNA having a mixed-base sequence can only form duplex structure. Biophysical assays at physiological pH revealed the formation of higher order structure in case of homo-pyrimidine PNA, whereas the mixed-base PNA was found to form a duplex structure with RNA. In vitro GTPase assay showed dose-dependent inhibitory effect of the homo-pyrimidine PNAs on SRP mediated GTP hydrolysis as compared to mixed-base PNA. Thus, our results show that the formation of higher order structures by homo-pyrimidine PNAs exhibit significant effect on RNA functionality than the mixed-base PNA.
In summary, we have proposed and validated SRP as a potential antibacterial target for the first time. Our results also suggest the importance of understanding the target site selection in order to develop better antisense molecules to target 4.5S RNA which will be a novel antibacterial target for multi-drug resistant bacteria. The approaches used here can also be generalized for discovery of other antibacterial targets for the development of broad-spectrum or even specific antibiotics.

Inhibition of bacterial signal recognition particle system by antisense PNA: A novel antibacterial strategy

In order to view the entire gallery of posters, videos, and other materials, please click "Submissions" below. 

To find the Q&A for each poster category, please click "Sessions" below. 

To ask a question, simply click on the session of interest. You will see a list of video presentations to the right. Below each video area, you'll see a section entitled 'Q&A for this presentation'. Here you can post questions to the presenters. They will be notified, and you'll also be notified when they reply to your question. You can expect that notification by email, and you'll find the author's response here.

27th CRSI National Symposium in Chemistry

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.