Probing the TRAP-RNA interaction with nucleoside analogs

Area of Science:

• Molecular Biology
• RNA-protein interactions
• Biochemistry

Background:

• The trp RNA-binding Attenuation Protein (TRAP) from Bacillus subtilis regulates gene expression by binding to trp leader mRNA.
• TRAP recognizes specific GAG and UAG repeat sequences within the mRNA.

Purpose of the Study:

• To identify the essential chemical groups on RNA for stable TRAP-RNA complex formation.
• To elucidate the specific roles of RNA nucleotides and their functional groups in TRAP binding.

Main Methods:

• Systematic substitution of nucleosides with analogs in a repetitive RNA sequence (UAGCC)11.
• Assessing the impact of these substitutions on TRAP-RNA binding affinity.
• Utilizing deoxyribonucleoside and base analog substitutions, including abasic nucleotides.

Main Results:

• A 2 eal-hydroxyl group on the third guanosine residue of RNA triplets is critical for high-affinity TRAP binding.
• Specific exocyclic functional groups and N1 nitrogens of adenine and guanine in the second and third triplet nucleotides are involved in binding.
• The AG dinucleotide within the triplet repeats primarily dictates TRAP-RNA complex specificity and stability.
• Certain RNA modifications, like N7-nitrogen of adenosine/guanosine and 2 eal-hydroxyls, can interfere with TRAP binding by inducing structural changes.

Conclusions:

• The TRAP-RNA interaction is highly specific, relying on precise chemical features of the RNA.
• The AG dinucleotide motif is the main determinant for TRAP recognition and binding.
• RNA structural elements, influenced by specific chemical groups, can modulate TRAP binding affinity.