Potential Binding Partners of cADPR and cADPR isomers in the Thoeris Phage Defense System
Date
2023-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Antibiotics were once hailed as wonder drugs but have led to increased
antibiotic resistance. This has become a major global issue, causing millions of deaths
annually and higher healthcare costs. The decline in antibiotic discovery and harmful
side effects further highlight the need for alternative treatments. Bacteriophage therapy
is an alternative approach to combat antibiotic resistance. Bacteriophages are viruses
that target and destroy bacteria. Unlike antibiotics, they are highly specific in their
infectivity and can coevolve with bacteria, making it harder for resistance to develop.
However, challenges include limited host range, safety concerns, regulatory issues,
and bacterial anti-phage systems. Understanding these bacterial anti-phage systems is
crucial for advancing bacteriophage therapies. The Thoeris System is an novel anti phage system found in bacteria. It relies on two proteins, ThsB and ThsA, to combat
phage infections.ThsB detects phages and produces a variant cyclic adenosine
diphosphate ribose (cADPR) molecule. ThsA binds to the cADPR which activated its
NADase activity, leading to premature bacterial death and phage elimination. The
Thoeris System utilizes 2'cADPR and 3'cADPR isomers as signaling molecules. The
Thoeris System can be countered by phages with Tad genes that sequester cADPR.
The discovery of new anti-phage systems is aided by analyzing defense islands in
bacterial genomes. This approach has led to identifying the Thoeris System and other
anti-phage systems. ThsC is a novel protein in the Thoeris System, belonging to the
HIT protein family. HIT proteins, including Hint1 and E.coli Hint, play roles in
cellular immunity and nucleotide hydrolysis. To find the function of ThsC in the
Thoeris Systems, cADPR isomers were purified and studied in enzymatic assays with
ThsC. Reactions were purified with HPLC and analyzed by Mass Spectrophotometry.
The function and role of ThsC still needs to be elucidated in regard to 3’cADPR,
ThsA, and ThsB.