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article:
doi: 10.1016/j.chom.2022.09.017
abstract: |
Bacterial anti-phage systems are frequently clustered in microbial genomes, forming defense islands. This property enabled the recent discovery of multiple defense systems based on their genomic co-localization with known systems, but the full arsenal of anti-phage mechanisms remains unknown. We report the discovery of 21 defense systems that protect bacteria from phages, based on computational genomic analyses and phage-infection experiments. We identified multiple systems with domains involved in eukaryotic antiviral immunity, including those homologous to the ubiquitin-like ISG15 protein, dynamin-like domains, and SEFIR domains, and show their participation in bacterial defenses. Additional systems include domains predicted to manipulate DNA and RNA molecules, alongside toxin-antitoxin systems shown here to function in anti-phage defense. These systems are widely distributed in microbial genomes, and in some bacteria, they form a considerable fraction of the immune arsenal. Our data substantially expand the inventory of defense systems utilized by bacteria to counteract phage infection.
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Sensor: Unknown
Activator: Unknown
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contributors:
- Helena Shomar, Marie Guillaume
relevantAbstracts:
- doi: 10.1016/j.chom.2022.09.017
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# Tiamat
## Description
This defense system is composed of one gene refered to as TmtA.
This systems is widespread across diverse prokaryotic phyla, and was experimentally validated in _Escherichia coli_ (confers protection against phages T6 and T5).
## Molecular mechanism
To our knowledge the molecular mechanism is unknown. Please update.
## Example of genomic structure
The Tiamat system is composed of one protein: TmtA_2599863134.
Here is an example found in the RefSeq database:
{max-width=750px}
Tiamat system in the genome of *Pseudomonas aeruginosa* (GCF_022638055.1) is composed of 1 protein: TmtA_2731770353 (WP_023121076.1).
## Distribution of the system among prokaryotes
The Tiamat system is present in a total of 228 different species.
Among the 22k complete genomes of RefSeq, this system is present in 342 genomes (1.5 %).
{max-width=750px}
*Proportion of genome encoding the Tiamat system for the 14 phyla with more than 50 genomes in the RefSeq database.*
## Structure
### Tiamat
::molstar-pdbe-plugin
---
height: 700
dataUrl: /tiamat/Tiamat__TmtA-plddts_86.46392.pdb
---
::
<mermaid>
graph LR;
Millman_2022[<a href='https://doi.org/10.1016/j.chom.2022.09.017'>Millman et al., 2022</a>] --> Origin_0
Origin_0[Bacillus cereus
<a href='https://img.jgi.doe.gov/cgi-bin/m/main.cgi?section=GeneDetail&page=geneDetail&gene_oid=2641244160'>2641244160</a>] --> Expressed_0[Escherichia coli]
Expressed_0[Escherichia coli] ----> T6 & T5
subgraph Title1[Reference]
Millman_2022
end
subgraph Title2[System origin]
Origin_0
end
subgraph Title3[Expression species]
Expressed_0
end
subgraph Title4[Phage infected]
T6
T5
end
style Title1 fill:none,stroke:none,stroke-width:none
style Title2 fill:none,stroke:none,stroke-width:none
style Title3 fill:none,stroke:none,stroke-width:none
style Title4 fill:none,stroke:none,stroke-width:none
</mermaid>