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To obtain insight into the genome-wide transcriptional response of heterologous carotenoid production in Saccharomyces cerevisiae, the transcriptome of two different S. cerevisiae strains overexpressing carotenogenic genes from the yeast Xanthophyllomyces dendrorhous grown in carbon-limited chemostat cultures was analysed. The strains exhibited different absolute carotenoid levels as well as different intermediate profiles. These discrepancies were further sustained by the difference of the transcriptional response exhibited by the two strains. Transcriptome analysis of the strain producing high carotenoid levels resulted in specific induction of genes involved in pleiotropic drug resistance (PDR). These genes encode ABC-type and major facilitator transporters which are reported to be involved in secretion of toxic compounds out of cells. β-Carotene was found to be secreted when sunflower oil was added to the medium of S. cerevisiae cells producing high levels of carotenoids, which was not observed when added to X. dendrorhous cells. Deletion of pdr10, one of the induced ABC transporters, decreased the transformation efficiency of a plasmid containing carotenogenic genes. The few transformants that were obtained had decreased growth rates and lower carotenoid production levels compared to a pdr5 deletion and a reference strain transformed with the same genes. Our results suggest that production of high amounts of carotenoids in S. cerevisiae leads to membrane stress, in which Pdr10 might play an important role, and a cellular response to secrete carotenoids out of the cell. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Kluyveromyces lactis is both scientifically and biotechnologically one of the most important non- Saccharomyces yeasts. Its biotechnological significance builds on its history of safe use in the food industry and its well-known ability to produce enzymes like lactase and bovine chymosin on an industrial scale. In this article, we review the various strains, genetic techniques and molecular tools currently available for the use of K. lactis as a host for protein expression. Additionally, we present data illustrating the recent use of proteomics studies to identify cellular bottlenecks that impede heterologous protein expression. [ABSTRACT FROM AUTHOR]

By sequence analysis of 96 randomly selected clones in a cDNA library of Xanthophyllomyces dendrorhous, ten novel, full-length clones encoding cytoplasmic ribosomal proteins (rp) were found. The deduced amino acid sequences showed significant homology to their counterparts from eukaryotic origin including mammals, fungi and plants. Some ribosmal protein encoding cDNAs appeared several times, but by Southern blot analysis it was shown they are encoded by a single copy gene. The nucleotide sequences of ten full length cDNAs were used to investigate the codon usage in X. dendrorhous. [ABSTRACT FROM AUTHOR]