Trehalose metabolism by Bacillus popilliae

Area of Science:

• Microbiology
• Biochemistry

Background:

• Bacillus popilliae utilizes sugars for growth.
• Trehalose is a disaccharide with known metabolic roles.
• Existing knowledge on trehalose degradation pathways in bacteria.

Purpose of the Study:

• To elucidate the trehalose degradation pathway in Bacillus popilliae NRRL B-2309MC.
• To investigate the enzymes and mechanisms involved in trehalose metabolism.
• To compare the pathway with those found in other organisms.

Main Methods:

• Enzyme activity assays (trehalase, trehalose phosphorylase, phosphotrehalase).
• Characterization of phosphotrehalase (purification, pH optimum, K(m)).
• Growth studies with wild-type and mutant strains.
• Metabolic labeling studies using [(14)C]trehalose and phosphoenolpyruvate (PEP).

Main Results:

• Trehalose is utilized more readily than glucose.
• Trehalase and trehalose phosphorylase activities were undetectable.
• Trehalose undergoes PEP-dependent phosphorylation to trehalose 6-phosphate.
• Phosphotrehalase cleaves trehalose 6-phosphate into glucose and glucose 6-phosphate.
• A phosphotrehalase mutant failed to grow on trehalose.
• Trehalose uptake involves transport as trehalose 6-phosphate via a PEP:sugar phosphotransferase system.

Conclusions:

• Bacillus popilliae employs a novel trehalose degradation pathway.
• The pathway involves PEP-dependent phosphorylation and phosphotrehalase activity.
• This unique pathway is crucial for trehalose utilization in this bacterium.