Interaction of structural modules in substrate binding by the ribozyme from Bacillus subtilis RNase P

Area of Science:

• Molecular Biology
• Biochemistry
• RNA Biology

Background:

• Bacterial ribonuclease P (RNase P) is a ribozyme crucial for tRNA maturation.
• RNase P recognizes specific structural modules within its tRNA substrate.
• Previous studies identified in vitro selected substrates that bind RNase P.

Purpose of the Study:

• To investigate the binding interactions between RNase P RNA and three in vitro selected substrates.
• To elucidate the structural basis of substrate recognition by RNase P.
• To compare the binding of selected substrates with that of natural tRNA substrates.

Main Methods:

• Chemical modification of RNase P RNA-substrate complexes using dimethylsulfate and kethoxal.
• Analysis of substrate binding sites on the RNase P RNA.
• Comparison of secondary structures between tRNA and selected substrates.

Main Results:

• All three selected substrates bind to the same surface on RNase P RNA that interacts with the tRNA T stem-loop.
• Selected substrates share a hairpin loop analogous to the tRNA T stem-loop but possess a non-helical linker.
• The T stem-loop and acceptor stem of both tRNA and selected substrates bind to distinct domains within the RNase P RNA.

Conclusions:

• RNase P RNA exhibits adaptable substrate recognition, binding both natural tRNAs and in vitro selected molecules.
• The identified binding mechanism highlights the importance of specific structural modules for ribozyme activity.
• These findings pave the way for isolating novel ribozyme-substrate pairs with interactive modules.