6M6U image
Entry Detail
PDB ID:
6M6U
Keywords:
Title:
Crystal structure the toxin-antitoxin MntA-HpeT mutant-D39ED41E
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2020-03-16
Release Date:
2020-09-30
Method Details:
Experimental Method:
Resolution:
2.35 Å
R-Value Free:
0.23
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
P 1 21 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Toxin-antitoxin system antitoxin MntA family
Mutations:D39E, D41E
Chain IDs:A, E (auth: F)
Chain Length:139
Number of Molecules:2
Biological Source:Shewanella oneidensis MR-1
Polymer Type:polypeptide(L)
Description:Toxin-antitoxin system toxin HepN family
Chain IDs:B, C, D, F (auth: G), G (auth: H), H (auth: I)
Chain Length:133
Number of Molecules:6
Biological Source:Shewanella oneidensis MR-1
Ligand Molecules
Primary Citation
Novel polyadenylylation-dependent neutralization mechanism of the HEPN/MNT toxin/antitoxin system.
Nucleic Acids Res. 48 11054 11067 (2020)
PMID: 33045733 DOI: 10.1093/nar/gkaa855

Abstact

The two-gene module HEPN/MNT is predicted to be the most abundant toxin/antitoxin (TA) system in prokaryotes. However, its physiological function and neutralization mechanism remains obscure. Here, we discovered that the MntA antitoxin (MNT-domain protein) acts as an adenylyltransferase and chemically modifies the HepT toxin (HEPN-domain protein) to block its toxicity as an RNase. Biochemical and structural studies revealed that MntA mediates the transfer of three AMPs to a tyrosine residue next to the RNase domain of HepT in Shewanella oneidensis. Furthermore, in vitro enzymatic assays showed that the three AMPs are transferred to HepT by MntA consecutively with ATP serving as the substrate, and this polyadenylylation is crucial for reducing HepT toxicity. Additionally, the GSX10DXD motif, which is conserved among MntA proteins, is the key active motif for polyadenylylating and neutralizing HepT. Thus, HepT/MntA represents a new type of TA system, and the polyadenylylation-dependent TA neutralization mechanism is prevalent in bacteria and archaea.

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