1 / 22

Diversity of Saccharomyces cerevisiae

Diversity of Saccharomyces cerevisiae. Linda F. Bisson Department of Viticulture and Enology University of California, Davis. What Is a Yeast Strain?. Members of the same genus and species Differ in a measurable way Differences can be neutral or impact cell phenotypes.

zena-smith
Download Presentation

Diversity of Saccharomyces cerevisiae

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Diversity of Saccharomycescerevisiae Linda F. Bisson Department of Viticulture and Enology University of California, Davis

  2. What Is a Yeast Strain? • Members of the same genus and species • Differ in a measurable way • Differences can be neutral or impact cell phenotypes

  3. What Is Strain Diversity? • Differences in information that is inherited • Differences in expression of inherited information

  4. What Causes Strain Diversity? • Differences in sequences of genes on nuclear chromosomes • Differences in position of gene sequences on chromosomes • Differences in organelle genomes or composition • Presence of extrachromosomal circular and linear nucleic acids • Inherited transcriptional states • Inherited protein conformational states

  5. Saccharomyces Nucleus Mitochondrion Secretory Pathway Golgi Vacuole Endoplasmic reticulum

  6. Daughter Cells Inherit • Full complement of mother cell’s chromosomes • Organelles: structure and DNA • Proteins, plasmids and expression patterns

  7. Sources of Inherited Information • Parental lineage • Lateral gene transfer: pick up of genetic information from environment • Hybrid formation with other related species or strains

  8. How Does Diversity Arise? • Change in DNA sequence • Change in position on chromosome • Development of prion state

  9. Gene Expression DNA mRNA Protein

  10. Gene Differences: Alleles • If gene sequence differs then protein sequence will differ • If protein sequence differs, activity may differ: • Amount of activity • Regulation of activity • Type of activity • Stability of activity

  11. How Are Gene Sequences Changed? • Oxidative damage of base pairs (reactive oxygen species derived from normal metabolism) • Misreading of base pairs (mistakes during DNA synthesis) • UV light damage to base pairs (failure of repair mechanisms) • Chemical agent damage (rare event)

  12. How Are Gene Sequences Changed? • Failure of mutation to be recognized and repaired • Makes cells more fit for their local environment • No selection against change

  13. How Does Diversity Arise? • Change in DNA sequence • Change in position on chromosome • Development of prion state

  14. What Are Chromosomes? • Linear pieces of DNA that carry genes, regulatory regions and spacer regions (Saccharomyces has 16) • Comprised of centromere (point of attachment to spindles during division) • Telomeres (ends) point of attachment to the nuclear membrane Centromere Chromosome Telomere

  15. Why Is Chromosome Position Important? • Position influences presence/absence of gene • Position influences level of expression • Position influences amplification of gene (number of copies)

  16. Impact of Position of Gene • In certain chromosomal areas basal level of expression is elevated (away from steric hindrance) • In certain chromosomal areas basal level of expression is decreased (near centromeres) • Gene adjacency can impact expression (interference from nearby genes)

  17. How Does Diversity Arise? • Change in DNA sequence • Change in position on chromosome • Development of prion state

  18. What Are Prions? • Protein-based inheritance • Proteins exist in different conformations • Conformation confers information • Most are stress-induced • Provide molecular memory of stress

  19. (Brown, Lindquist, 2009) [gar-] Presence of Glucose recognized and signal transduced by Rgt2/Snf3 to Yck1/2 which phosphorylate Std1 and Mth1, thus marking them for degradation. Rgt1 remains free in the cytosol, Hxt3 is still expressed. [GAR+] In absence of glucose or in [GAR+] Std1 interacts with Pma1, possibly altering Std1 affinity for Rgt1. They associate as a complex and enter the nucleus, inhibit HXT3 expression, leading to a 36 fold down-regulation of Hxt3! This alternate pathway is maintained as a dominant, heritable prion shift.

  20. Wine Yeast Strain Diversity Significant diversity exists among wine strains: • Presence/absence of genes • Allele differences (single nucleotide polymorphisms) • Chromosomal rearrangement is found • Differences in prion state are found

  21. What Does Wine Strain Diversity Mean? • Differences in fermentation parameters • Ability to dominate fermentation varies • Aroma compounds vary in type and concentration • Mouth feel factors differ • Sensitivity to stress varies

  22. First Flight: Saccharomyces cerevisiae Strains • Glass 1: VL1 • Glass 2: Rhone 4600 • Glass 3: BC • Glass 4: CKS-102 • Glass 5: M2 • Glass 6: Zymaflore X16

More Related