Solution structure and function of YndB, an AHSA1 protein from Bacillus subtilis

Area of Science:

• Structural Biology
• Biochemistry
• Microbiology

Background:

• The Bacillus subtilis protein YndB's function was previously unknown.
• YndB shares structural similarities with eukaryote protein Aha1, an activator of Hsp90 ATPase.
• Aha1's role in Hsp90 regulation suggests potential stress response involvement for YndB.

Purpose of the Study:

• To determine the solution structure of Bacillus subtilis YndB using NMR spectroscopy.
• To investigate the biological functions and binding properties of YndB.
• To explore YndB's potential role in stress response and inter-kingdom signaling.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy to solve the solution structure of YndB.
• Sequence and structure comparisons to identify homologous proteins.
• In silico screening of a lipid library to predict binding molecules.
• 2D (1H-15N) HSQC NMR titration experiments to verify binding interactions.

Main Results:

• The YndB structure revealed a helix-grip fold with a hydrophobic cavity.
• YndB preferentially binds lipid-like molecules, particularly chalcone/hydroxychalcone, flavanone, and flavone/flavonol classes.
• Binding affinities were confirmed via NMR titrations with specific chalcone and flavonoid compounds.
• YndB is classified as an activator of Hsp90 ATPase homolog 1-like protein (AHSA1).

Conclusions:

• YndB functions as an AHSA1 protein involved in stress response.
• YndB likely interacts with plant-derived chalcone-like flavonoids.
• This interaction suggests a role for YndB in the symbiotic relationship between Bacillus subtilis and plants, potentially mediating stress responses to plant-released compounds.