crispr and superbugs
TRANSCRIPT
CRISPR And Superbugs
Guided by: Dr. Rajnikant G.K.
Made and Presented By : Amay Redkar, B130855BT
Hallmarks of CRISPRs • Adaptive Immunity of
sorts in Bacteria and Archaea
• Provides Defence against bacteriophages
• Shares no phylogenetic relationship with eukaryotic immune system
CRISPR RepeatImage Source: Bolotin et. al. 2005
Fragment from a Viral genome
3 Steps To Acquire Immunity In Bacteria
• Given system was first identified in Streptococcus pyogenes
• Recognition and adaptation
• Expression• Interference
Image Source: Weidenheft et. al. 2012
Cas9 Endonuclease Mechanism
• Protospacer Adjacent Motif (PAM)
• Trans-activating crRNA (tracrRNA)
• CRISPR RNA (crRNA)• Double Strand Breaks(DSBs)
Image Source: Jinek et. al. 2012
Genome Editing and DSBs
Image Source: Khalili et. al. 2015 & Ran et al. 2013
Sgrna - Single Guide RNANHEJ - Non-homologous End-joiningHDR - Homology Directed Repair
Advantages of CRISPR in Genome Editing
• 2 component model for genome engineering cleaving enzyme• Relies on RNA-DNA base pairing for site recognition, instead of
protein.• Cas9 mediated editing is efficient, site-specific and can be multiplexed• Drastically but relatively cheap
Superbug Infections• Widespread can and will be fatal for us as a species• High mortality rate• Resistance can be developed • In cell or• Acquired via Horizontal transfer
• But what is so different?• Mechanism-Pumpers and Chewers • E.g. MRSA, CRE, C. difficile, tuberculosis and Klebsiella• Case -The Nevada Woman
Image Source: Ross et. al. 2014
• RNA Guided Nucleases(RGN)
Advantages of CRISPR as a Antimicrobial Agent
•Unprecedented Specificity, not just narrow spectrum but targeting bugs that have specific genes only
•Development of anti CRISPR genes is not viable for cells because of the extreme competition from phages.