Multiple gene copy number increases total protein expression and enzyme activity of DNA topoisomerase I in <i>Pichia pastoris</i>

The present study aimed to employ an in vivo strategy for the establishment of multi‑copy gene constructs human DNA topoisomerase I (hTopI) using pPIC3.5K vector in Pichia. clones with inserts (His+ transformants) that were able survive highest concentration Geneticin® found express expression level total protein and exhibited target enzyme activity. was 1.76 mg/ml GS115‑pPIC3.5K‑hTop1, which resistant 1.00 Geneticin at 48 h incubation. activity hTopI also observed culture expressed by GS115‑pPIC3.5K‑hTopI, (19.7x104 Ul/OD600). On whole, provides information regarding production from recombinant Pichia only a shaker flask system, can be further developed as in‑house resource screening potential anticancer agents.