Structural insights into HetR-PatS interaction involved in cyanobacterial pattern formation

Area of Science:

• Microbiology
• Structural Biology
• Developmental Biology

Background:

• Cyanobacteria differentiation into heterocysts is crucial for nitrogen fixation.
• The HetR transcription factor and PatS peptide are key regulators of this process.
• Understanding their interaction mechanism is vital for deciphering developmental patterns.

Purpose of the Study:

• To elucidate the structural basis of HetR-DNA and HetRHood-PatS6 interactions.
• To provide mechanistic insights into the regulation of heterocyst patterning in Anabaena.
• To explore the structural underpinnings of a prokaryotic Turing model.

Main Methods:

• X-ray crystallography was used to determine the structures of HetR-DNA and HetRHood-PatS6 complexes.
• High-resolution structural analysis at 2.80 Å and 2.10 Å.
• Analysis of novel HTH motifs and conformational changes.

Main Results:

• The intertwined HetR dimer features novel HTH motifs involving auxiliary α-helices.
• PatS6 peptides bind to HetRHood, inducing conformational changes.
• These changes lead to the dissociation of auxiliary helices and release of HetR from DNA.

Conclusions:

• The study provides the first structural evidence for HetR-DNA and HetRHood-PatS6 interactions.
• Reveals a novel mechanism of transcriptional regulation mediated by peptide binding.
• Offers structural insights into a prokaryotic Turing model for pattern formation.