4I8O: Crystal structure of the toxin RnlA from Escherichia coli

Escherichia coli RnlA-RnlB is a newly identified toxin-antitoxin (TA) system that plays a role in bacteriophage resistance. RnlA functions as a toxin with mRNA endoribonuclease activity and the cognate antitoxin RnlB inhibits RnlA toxicity in E. coli cells. Interestingly, T4 phage encodes the antitoxin Dmd, which acts against RnlA to promote its own propagation, suggesting that RnlA-Dmd represents a novel TA system. Here, we have determined the crystal structure of RnlA refined to 2.10 (Dmd-binding domain), which is an organization not previously observed among known toxin structures. Small-angle X-ray scattering (SAXS) analysis revealed that RnlA forms a dimer in solution via interactions between the DBDs from both monomers. The in vitro and in vivo functional studies showed that among the three domains, only the DBD is responsible for recognition and inhibition by Dmd and subcellular location of RnlA. In particular, the helix located at the C-terminus of DBD plays a vital role in binding Dmd. Our comprehensive studies reveal the key region responsible for RnlA toxicity and provide novel insights into its structure-function relationship.
PDB ID: 4I8ODownload
MMDB ID: 114484
PDB Deposition Date: 2012/12/4
Updated in MMDB: 2014/12
Experimental Method:
x-ray diffraction
Resolution: 2.104  Å
Source Organism:
Similar Structures:
Biological Unit for 4I8O: monomeric; determined by author
Molecular Components in 4I8O
Label Count Molecule
Protein (1 molecule)
Toxin Rnla(Gene symbol: rnlA)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB