Phage Evolved Medicine with Travis Blum

Episode Summary: Enzymes that break down other proteins, or proteases, could be used as a powerful therapeutic if they could specifically chew-up disease causing entities. However many proteases are non-specific, breaking any protein in their path, while the specific ones target proteins that would provide no therapeutic benefit. Travis and his colleagues developed a riff on the method known as PANCE that utilizes bacteria and bacterial viruses known as phages to evolve proteins toward a specific goal. With it, he retrains the sequence-specific protease, botulinum neurotoxin, toward new targets and away from its original ones. The novel enzymes Travis generates have the potential to not only stimulate nerve regeneration but also deliver itself to the correct cell types for a whole new type of therapy. 

Episode Notes:

About the Author

• Travis is a postdoc who performed this work in the lab of Professor David Liu at Harvard University. The Liu lab is famous for engineering and evolving proteins that can be utilized as massively impactful tools for overcoming diverse diseases.  
• Travis’s teachers fostered a curiosity that created a passion for chemistry and ultimately led him to engineer new biochemistries. 

Key Takeaways

• Proteases are enzymes that cut up other proteins.
• Proteases can either be non-specific, a nuke obliterating any protein in their path,  or sequence-specific, a heat seeking missile only cutting very specific protein motifs.
• Sequence-specific proteases that target disease causing proteins would make great drugs but therapeutically useful proteases rarely exist in nature.
• Travis focuses on re-engineering the sequence-specific protease known as botulinum neurotoxin so that it cuts an entirely new, therapeutically relevant protein sequence.
• Using a method called PANCE that utilizes bacteria and bacterial viruses (phages), Travis trains botulinum neurotoxin toward cutting a new target and leaving its original target alone.

Translation

• Botulinum neurotoxin has a cutting domain that Travis engineered toward a therapeutically relevant target, and a targeting domain that delivers the protein toward neurons.
• The enzymes generated could be used to cure neural pathologies but the PANCE could also be applied to change which cell type the protease targets, creating a highly programmable therapeutic protease platform.
• The platform has a ton of interest from industry and Travis is continuing to work on it outside of academia so that these proteases make it to the clinic and impact patient lives.

First Author: Travis Blum

Paper: 

Phage-assisted evolution of botulinum neurotoxin proteases with reprogrammed specificity