An engineered yeast cytosine deaminase with improved catalytic activity and stability for macrophage-mediated enzyme/prodrug therapy.

ABSTRACT: Utilization of yeast cytosine deaminase (yCD) to activate the prodrug 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU) at the target site is an attractive strategy for overcoming the narrow therapeutic index of 5-FU. Nevertheless, protein delivery of yCD is challenging in part due to its thermal instability. Herein, we have rationally engineered a mutant yCD by replacing Met100 situated at the active site entry with the bulkier histidine to hinder potential oxidation of the active site Cys91. The engineered yCD-Met100His exhibits significantly enhanced activity and thermal stability. yCD-M100H is then genetically fused to the crystal-forming protein Cry3Aa to generate Cry3Aa-yCD-M100H fusion crystals to facilitate the enzyme's uptake into macrophages. The resulting Cry3Aa-yCD-M100H-loaded

SUBMITTER: Zheng J 

PROVIDER: S-EPMC12615592 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature