Pyrroline-5-carboxylate reductase

Pyrroline-5-carboxylate reductase (P5CR) is an enzyme that plays a crucial role in the metabolism of proline, an amino acid involved in various physiological processes. P5CR catalyzes the conversion of pyrroline-5-carboxylate (P5C) to proline, utilizing NAD(P)H as a cofactor. This enzymatic reaction is essential for maintaining the balance of proline levels in cells.

Function

P5CR is a key enzyme in the proline biosynthesis pathway. Proline is an important amino acid involved in protein synthesis, stress response, and osmotic regulation. P5CR helps regulate proline levels by converting P5C, an intermediate metabolite, into proline. This conversion is crucial for maintaining cellular homeostasis and responding to various environmental stresses.

Structure

P5CR is a homodimeric enzyme, meaning it consists of two identical subunits. Each subunit contains a conserved NAD(P)H-binding domain and a catalytic domain responsible for the conversion of P5C to proline. The active site of P5CR contains several amino acid residues that are essential for substrate binding and catalysis.

Role in Disease

Dysregulation of P5CR activity has been implicated in several diseases. For example, increased P5CR activity has been observed in certain types of cancer, including breast and lung cancer. This upregulation of P5CR is thought to contribute to tumor growth and survival by promoting proline synthesis, which can provide energy and protect against oxidative stress. Conversely, decreased P5CR activity has been associated with neurodegenerative disorders, such as Alzheimer's disease, where proline metabolism is disrupted.

Importance in Plants

P5CR is particularly important in plants due to their reliance on proline for stress tolerance. Plants often encounter adverse environmental conditions, such as drought, high salinity, and extreme temperatures. Proline accumulation in plants helps protect cellular structures and maintain water balance during these stressful conditions. P5CR plays a crucial role in proline biosynthesis, enabling plants to adapt and survive under unfavorable circumstances.

References

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See Also

• Proline
• Enzyme
• Metabolism