Open AccessStructural basis of amino acid surveillance by higher-order tRNA-mRNA interactions
Author(s) -
Shuang Li,
Zhaoming Su,
J. Lehmann,
Vassiliki Stamatopoulou,
Νικολέτα Γιαρίμογλου,
Frances E. Henderson,
Fan Li,
Grigore Pintilie,
Kaiming Zhang,
Muyuan Chen,
Steven J. Ludtke,
Yun-Xing Wang,
Constantinos Stathopoulos,
Wah Chiu,
Jinwei Zhang
Publication year - 2019
Publication title -
nature structural and molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.448
H-Index - 270
eISSN - 1545-9993
pISSN - 1545-9985
DOI - 10.1038/s41594-019-0326-7
Subject(s) - aminoacylation , transfer rna , riboswitch , wobble base pair , biology , translation (biology) , rna , pseudoknot , amino acid , protein biosynthesis , t arm , genetics , gene , microbiology and biotechnology , messenger rna , non coding rna
Amino acid availability in Gram-positive bacteria is monitored by T-box riboswitches. T-boxes directly bind tRNAs, assess their aminoacylation state, and regulate the transcription or translation of downstream genes to maintain nutritional homeostasis. Here, we report cocrystal and cryo-EM structures of Geobacillus kaustophilus and Bacillus subtilis T-box-tRNA complexes, detailing their multivalent, exquisitely selective interactions. The T-box forms a U-shaped molecular vise that clamps the tRNA, captures its 3' end using an elaborate 'discriminator' structure, and interrogates its aminoacylation state using a steric filter fashioned from a wobble base pair. In the absence of aminoacylation, T-boxes clutch tRNAs and form a continuously stacked central spine, permitting transcriptional readthrough or translation initiation. A modeled aminoacyl disrupts tRNA-T-box stacking, severing the central spine and blocking gene expression. Our data establish a universal mechanism of amino acid sensing on tRNAs and gene regulation by T-box riboswitches and exemplify how higher-order RNA-RNA interactions achieve multivalency and specificity.