Bacillus subtilis exhibits MnmC-like tRNA modification activities

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• The MnmE-MnmG complex in E. coli modifies tRNA wobble uridine.
• MnmC enzyme converts modifications to 5-methylaminomethyl via oxidoreductase (MnmC(o)) and methyltransferase (MnmC(m)) activities.
• MnmE and MnmG are conserved, but MnmC is not; B. subtilis lacks MnmC homologs.

Purpose of the Study:

• Investigate the presence of 5-methylaminomethyl modification in Bacillus subtilis tRNA.
• Determine if B. subtilis possesses MnmC(o) and MnmC(m) activities despite lacking MnmC homologs.
• Explore the evolutionary implications of tRNA modification in B. subtilis.

Main Methods:

• Analysis of tRNA modifications in B. subtilis.
• Comparative genomics to identify potential MnmC-like activities.

Main Results:

• The 5-methylaminomethyl modification was found to be prevalent in B. subtilis tRNA^Gln_UUG and tRNA^Glu_UUC.
• B. subtilis appears to possess MnmC(o)- and MnmC(m)-like activities within non-MnmC homologous proteins.
• This challenges the assumption that the glycine pathway is the sole route for tRNA modification in this species.

Conclusions:

• B. subtilis has evolved alternative mechanisms to perform MnmC-like tRNA modifications.
• These evolved activities likely confer a biological advantage, highlighting functional convergence in tRNA modification pathways.
• The findings expand our understanding of tRNA modification diversity beyond conserved MnmC enzymes.