Towards highly efficient gene targeting in a human pathogenic yeast Cryptococcus neoformans

Abstract

DNA double strand breaks are repaired through nonhomologous end joining (NHEJ) or homologous recombination (HR) in the eukaryotes from yeast to human. These systems have been applied for foreign DNA introduction into the host genome. In 2004, researchers discovered that inactivation of proteins involved in NHEJ leads highly efficient HR in a filamentous fungus Neurospora crassa. In a human pathogenic yeast Cryptococcus neoformans, NHEJ occurs quite often so that a large number of transformants should be determined before obtaining the genetically engineered strains with desired integration by HR. We disrupted genes coding for DNA ligase IV or so called KU proteins, which are responsible for NHEJ in C. neoformans. The strains were indistinguishable in growth and other phenotypes, but the HR efficiencies were elevated.