engleski

Replication elements in the wine yeast Dekkera bruxellensis

The wine yeast Dekkera bruxellensis is adapted to environmental conditions that are particularly harsh and limiting. It is asexual, and its different strains’ chromosomes greatly vary in number and organization. In the present study we isolated and described the replication elements o f D. bruxellensis. For this purpose we first created auxotrophic strains, prepared genomic libraries, and developed a transformation protocol. Surprisingly, from two different strains, only three different loci (named CIGO1, CIGO2and CIGO3) were subcloned and supported autonomous replication. The CIGO loci differ from the known yeast CEN elements, and their biological activity was retained within only the 600-900bp segments. For the three loci, the plasmid loss in the non-selective medium was between 20 -75%. The reporter gene expression indicated that the copy number exceeded ten per cell. In the tested strains having very different karyotypes, each CIGO loci hybridized to at least one chromosome, but each chromosome hybridized to only one of the three CIGO loci. In the recently sequenced genome of Y879, two CIGO loci are overrepresented in the genome sequence and thereby present in several copies. These properties suggest that the CIGO loci could function as a base for a new replication unit, for example a new chromosome, which thereby could increase genome dynamics. An enhanced ability to rearrange the genome could be an efficient tool to exploit new and demanding niches.

Dekkera bruxelensis; replication elements; transformation

nije evidentirano