Download MendeleyDefining the mRNA recognition signature of a bacterial toxin protein.
Schureck, M.A., Dunkle, J.A., Maehigashi, T., Miles, S.J., Dunham, C.M.(2015) Proc Natl Acad Sci U S A 112: 13862-13867
- PubMed: 26508639
- DOI: https://doi.org/10.1073/pnas.1512959112
- Primary Citation of Related Structures:
4PX8, 4W4G, 4YPB, 4YZV - PubMed Abstract:
Bacteria contain multiple type II toxins that selectively degrade mRNAs bound to the ribosome to regulate translation and growth and facilitate survival during the stringent response. Ribosome-dependent toxins recognize a variety of three-nucleotide codons within the aminoacyl (A) site, but how these endonucleases achieve substrate specificity remains poorly understood. Here, we identify the critical features for how the host inhibition of growth B (HigB) toxin recognizes each of the three A-site nucleotides for cleavage. X-ray crystal structures of HigB bound to two different codons on the ribosome illustrate how HigB uses a microbial RNase-like nucleotide recognition loop to recognize either cytosine or adenosine at the second A-site position. Strikingly, a single HigB residue and 16S rRNA residue C1054 form an adenosine-specific pocket at the third A-site nucleotide, in contrast to how tRNAs decode mRNA. Our results demonstrate that the most important determinant for mRNA cleavage by ribosome-dependent toxins is interaction with the third A-site nucleotide.
Organizational Affiliation:
Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322.
