Alarmone ppGpp directly inhibits tRNA-modifying enzyme MnmE in Bacillus subtilis, affecting biofilm
In Bacillus subtilis, the stress signal ppGpp acts on a tRNA-modification enzyme, which alters translation at AAG codons and controls biofilm matrix production, authors report.
Researchers reported in Science Advances that the alarmone guanosine tetraphosphate (ppGpp) directly inhibits MnmE (TrmE), a conserved GTPase that modifies tRNA. The enzyme is required for methylaminomethyl (mnm) modification of wobble uridine science.org
Science Advancesscience.orgOpen source ↗. The work links bacterial stress signaling to codon-specific translational control.
Using high-resolution ribosome profiling in Bacillus subtilis, the authors found that loss of MnmE selectively increases ribosome pausing at AAG codons. It also reprograms translation of a subset of genes, including small open reading frames.
Among them is a previously unrecognized AAG-containing leader peptide that controls expression of the biofilm repressor AbrB. Consistent with this, mnmE mutants produce extracellular matrix constitutively and bypass the biofilm defect of a relA mutant. The authors describe a pathway connecting ppGpp signaling, tRNA modification, codon-specific translation and multicellular development.
