Genomic diversity, chromosomal rearrangements, and interspecies hybridization in the Ogataea polymorpha species complex.

The methylotrophic yeast Ogataea polymorpha has long been a useful system for recombinant protein production, as well as a model system for methanol metabolism, peroxisome biogenesis, thermotolerance, and nitrate assimilation. It has more recently become an important model for the evolution of mating-type switching. Here, we present a population genomics analysis of 47 isolates within the O.

Carbon source requirements for mating and mating-type switching in the methylotrophic yeasts Ogataea (Hansenula) polymorpha and Komagataella phaffii (Pichia pastoris).

The methylotrophic yeasts Ogataea (Hansenula) polymorpha and Komagataella phaffii (Pichia pastoris) have important industrial applications and are models for several biological processes including peroxisome biology and methanol metabolism. We examined the carbon source requirements for mating-type (MAT) switching and mating in both species. Haploid strains of O.

Flip/flop mating-type switching in the methylotrophic yeast Ogataea polymorpha is regulated by an Efg1-Rme1-Ste12 pathway.

In haploid cells of Ogataea (Hansenula) polymorpha an environmental signal, nitrogen starvation, induces a reversible change in the structure of a chromosome. This process, mating-type switching, inverts a 19-kb DNA region to place either MATa or MATα genes under centromeric repression of transcription, depending on the orientation of the region. Here, we investigated the genetic pathway that controls switching.

An Evolutionary Perspective on Yeast Mating-Type Switching.

Cell differentiation in yeast species is controlled by a reversible, programmed DNA-rearrangement process called mating-type switching. Switching is achieved by two functionally similar but structurally distinct processes in the budding yeast and the fission yeast In both species, haploid cells possess one active and two silent copies of the mating-type locus (a three-cassette structure), the active locus is cleaved, and synthesis-dependent strand annealing is used to replace it with a copy of a silent locus encoding the opposite mating-type information. Each species has its own set of components responsible for regulating these processes.

Comparative genomics of biotechnologically important yeasts.

Ascomycete yeasts are metabolically diverse, with great potential for biotechnology. Here, we report the comparative genome analysis of 29 taxonomically and biotechnologically important yeasts, including 16 newly sequenced. We identify a genetic code change, CUG-Ala, in Pachysolen tannophilus in the clade sister to the known CUG-Ser clade.

Centromeres of the Yeast Komagataella phaffii (Pichia pastoris) Have a Simple Inverted-Repeat Structure.

Centromere organization has evolved dramatically in one clade of fungi, the Saccharomycotina. These yeasts have lost the ability to make normal eukaryotic heterochromatin with histone H3K9 methylation, which is a major component of pericentromeric regions in other eukaryotes. Following this loss, several different types of centromere emerged, including two types of sequence-defined ("point") centromeres, and the epigenetically defined "small regional" centromeres of Candida albicans Here we report that centromeres of the methylotrophic yeast Komagataella phaffii (formerly called Pichia pastoris) are structurally defined.

Mating-type switching by chromosomal inversion in methylotrophic yeasts suggests an origin for the three-locus Saccharomyces cerevisiae system.

Saccharomyces cerevisiae has a complex system for switching the mating type of haploid cells, requiring the genome to have three mating-type (MAT)-like loci and a mechanism for silencing two of them. How this system originated is unknown, because the three-locus system is present throughout the family Saccharomycetaceae, whereas species in the sister Candida clade have only one locus and do not switch. Here we show that yeasts in a third clade, the methylotrophs, have a simpler two-locus switching system based on reversible inversion of a section of chromosome with MATa genes at one end and MATalpha genes at the other end.

Comparative transcriptome analysis of obligately asexual and cyclically sexual rotifers reveals genes with putative functions in sexual reproduction, dormancy, and asexual egg production.

Background: Sexual reproduction is a widely studied biological process because it is critically important to the genetics, evolution, and ecology of eukaryotes. Despite decades of study on this topic, no comprehensive explanation has been accepted that explains the evolutionary forces underlying its prevalence and persistence in nature. Monogonont rotifers offer a useful system for experimental studies relating to the evolution of sexual reproduction due to their rapid reproductive rate and close relationship to the putatively ancient asexual bdelloid rotifers.

Inventory and phylogenetic analysis of meiotic genes in monogonont rotifers.

A long-standing question in evolutionary biology is how sexual reproduction has persisted in eukaryotic lineages. As cyclical parthenogens, monogonont rotifers are a powerful model for examining this question, yet the molecular nature of sexual reproduction in this lineage is currently understudied. To examine genes involved in meiosis, we generated partial genome assemblies for 2 distantly related monogonont species, Brachionus calyciflorus and B.