Dissecting how phages modulate bacterial immunity - structural basis of dNTPase inhibition by T7-like phages
Lead Research Organisation:
Durham University
Department Name: Biosciences
Abstract
Bacteriophages are viruses that can infect and kill bacteria. Phage Therapy against multi-drug resistant bacteria (currently in clinical trials) exploits this property. However, bacteria have evolved self-defence mechanisms. CRISPR-Cas, which is routinely used as a tool for gene editing, forms the "adaptive" immune system, while other bacterial proteins such as the dNTPase enzyme form the "innate" immune system.
The bacterial dNTPase, the focus of this proposal, blocks phage replication by depleting the supply of DNA building blocks (dNTPs) that the phage needs to replicate. This important mechanism is also conserved in vertebrates, with the human dNTPase homologue, SAMHD1, restricting the replication of pathogenic viruses such as HIV, the causative agent of AIDS.
Due to the importance of dNTPases in bacterial and human innate immunity, human-infecting viruses and phages have evolved their own "counter-attack" against the host dNTPase. T7-like phages, one superfamily used in Phage Therapy, produce a protein called gp1.2 that inhibits the dNTPase to increase the supply of dNTPs to enable phages to replicate their DNA genome. However, while all bacteria encode a dNTPase, not all phages have evolved a dNTPase-targeting gp1.2 protein.
This proposal aims to improve the efficacy of Phage Therapy against the opportunistic human pathogen Pseudomonas aeruginosa (P. aeruginosa). First, the project aims to characterise how P. aeruginosa dNTPase is inhibited by T7-like phage gp1.2 protein using X-ray crystallography, cryo-electron microscopy (cryoEM) and complementary biophysical methods. Secondly, a structure-guided approach will be used to mutate gp1.2 amino acid sequence to improve its ability to silence the P. aeruginosa dNTPase.
Overall, we will determine at the molecular level how the T7-like phage gp1.2 protein shuts down P. aeruginosa innate immunity protein dNTPase. This could improve the efficacy of future Phage Therapy against this bacterium and other human pathogens.
The bacterial dNTPase, the focus of this proposal, blocks phage replication by depleting the supply of DNA building blocks (dNTPs) that the phage needs to replicate. This important mechanism is also conserved in vertebrates, with the human dNTPase homologue, SAMHD1, restricting the replication of pathogenic viruses such as HIV, the causative agent of AIDS.
Due to the importance of dNTPases in bacterial and human innate immunity, human-infecting viruses and phages have evolved their own "counter-attack" against the host dNTPase. T7-like phages, one superfamily used in Phage Therapy, produce a protein called gp1.2 that inhibits the dNTPase to increase the supply of dNTPs to enable phages to replicate their DNA genome. However, while all bacteria encode a dNTPase, not all phages have evolved a dNTPase-targeting gp1.2 protein.
This proposal aims to improve the efficacy of Phage Therapy against the opportunistic human pathogen Pseudomonas aeruginosa (P. aeruginosa). First, the project aims to characterise how P. aeruginosa dNTPase is inhibited by T7-like phage gp1.2 protein using X-ray crystallography, cryo-electron microscopy (cryoEM) and complementary biophysical methods. Secondly, a structure-guided approach will be used to mutate gp1.2 amino acid sequence to improve its ability to silence the P. aeruginosa dNTPase.
Overall, we will determine at the molecular level how the T7-like phage gp1.2 protein shuts down P. aeruginosa innate immunity protein dNTPase. This could improve the efficacy of future Phage Therapy against this bacterium and other human pathogens.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| BB/T008695/1 | 01/10/2020 | 30/09/2028 | |||
| 2836187 | Studentship | BB/T008695/1 | 01/10/2023 | 30/09/2027 |