Some properties of trehalase from Phycomyces blakesleeanus

Area of Science:

• Biochemistry
• Enzymology
• Mycology

Background:

• Trehalase (alpha, alpha-trehalase glucohydrolase EC 3.2.1.28) is crucial for carbohydrate metabolism.
• Phycomyces spores exhibit dormancy, a state influenced by enzymatic activity.
• Understanding trehalase's role in spore dormancy is key to fungal biology.

Purpose of the Study:

• To investigate the biochemical properties of trehalase in dormant and activated Phycomyces spores.
• To explore the relationship between spore dormancy, trehalase activity, and environmental factors.

Main Methods:

• Enzyme activity assays under varying substrate concentrations.
• Determination of kinetic parameters (K-m) and substrate binding effects.
• Analysis of molecular weight via gel filtration.
• Thermostability and inhibition studies using ATP and other nucleosidephosphates.
• Controlled heating experiments to induce dormancy breaking and trehalase activation.

Main Results:

• Trehalase exists in two interconvertible forms: low-activity (dormant) and high-activity (activated).
• No differences in molecular weight (approx. 210,000) or electrophoretic mobility were observed between forms.
• Activated spores follow Michaelis-Menten kinetics (K-m ≈ 55 mM), while dormant spores show negative cooperativity.
• Dormant trehalase is less thermostable and more sensitive to ATP inhibition.
• Partial dormancy breaking and trehalase activation occur between 38-44°C.

Conclusions:

• Spore dormancy in Phycomyces is closely linked to the activation state of trehalase.
• Trehalase activation involves changes in enzyme kinetics, thermostability, and ATP sensitivity.
• Environmental cues like temperature can modulate trehalase activity and break spore dormancy.