Mapping Hfq-RNA interaction surfaces using tryptophan fluorescence quenching.

Area of Science:

• Molecular Biology
• Microbiology
• Biochemistry

Background:

• Hfq protein acts as a posttranscriptional riboregulator and RNA chaperone.
• Hfq regulates gene expression in response to environmental changes by binding small RNAs and mRNAs.
• Understanding Hfq-RNA binding sites is crucial for deciphering its regulatory mechanisms.

Purpose of the Study:

• To develop and apply a novel Hfq-RNA mapping approach.
• To identify specific Hfq binding sites on various RNA sequences.
• To investigate differences in Hfq binding between bacterial species.

Main Methods:

• Utilized single tryptophan-substituted Hfq proteins.
• Employed tryptophan fluorescence quenching (TFQ) to detect proximal RNA binding.
• Tested binding of various RNA sequences to Hfq from Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes.

Main Results:

• TFQ successfully identified distal and proximal Hfq binding sites for different RNA sequences.
• Discovered distinct binding preferences for Hfq from Gram-negative and Gram-positive bacteria.
• Redefined the Hfq distal face binding motif from (A-R-N)n to (A-A-N)n.
• Showed that the 5'-untranslated region of hfq mRNA binds both faces of E. coli Hfq.

Conclusions:

• The TFQ method is effective for mapping Hfq-RNA interactions.
• Hfq exhibits species-specific RNA binding site preferences.
• The identified binding motifs provide insights into Hfq-mediated gene regulation.