The pso4-1 mutant was characterized as deficient in some types of recombination, including gene conversion, crossing over, and intrachromosomal recombination. The mode of interaction between pso4-1 and rad51 and between pso4-1 and rad52 mutants indicated that the PSO4 gene belongs to the RAD52 epistasis group for strand-break repair. Moreover, the presence of the pso4-1 mutation decreased 8-MOP-photoinduced mutagenesis of the rad51 and rad52 mutants. Complementation tests using heterozygous diploid strains showed that the pso4 protein might interact with the rad52 protein during repair of 8-mop photolesions. The pso4-1 mutant, even though defective in inter- and intra-chromosomal recombination, conserves the ability for plasmid integration of circular and linear plasmid DNA. On the other hand, similar to the rad51 mutant, pso4-1 was able to incise but did not restore high-molecular-weight DNA during the repair of cross links induced by 8-MOP plus UVA. These results, together with those of previous reports, indicate that the PSO4 gene belongs to the RAD52 DNA repair group and its product participates in the DNA rejoining step of the repair of cross-link lesions, which are crucial for induced mutagenesis and recombinogenesis.
NADP + -dependent glutamate dehydrogenase (NADP + -Gdh) is the first step in ammonia assimilation pathway in Saccharomyces cerevisiae and the knowledge of its regulation is the key for many biotechnological purposes such as single cell protein production. The regulation of NADP + -Gdh activity in Kluyveromyces marxianus cells was evaluated under different ammonia supply in batch cultivations. The results showed that K. marxianus NADP + -Gdh activity is induced over a narrow range of extracellular ammonia supply, being repressed by both high ammonia concentration and the glutamate formed. This activity is not growth-associated and may function mainly to trace low amounts of ammonia after growth cessation. The results demonstrated that NADP + -Gdh may not be the main enzyme for ammonia assimilation in K. marxianus, as it has been postulated for K. lactis, instead is subjected to the same regulatory mechanism described for S. cerevisiae.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.