Molecular Cell Biology of the Yeast Saccharomyces cerevisiae

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Molecular Cell Biology of the Yeast
Saccharomyces cerevisiae

• Lecture III Molecular Logic of Asymmetry
• Zhang Yi,
• National Institute of Biological Sciences,
  20080628

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Cellular Anatomy
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Mitosis V.S Meiosis
a
a
a
a
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Mating Type Switch
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Mating Type Specific Gene

• MATa gene expression
• a1 mRNA from MATa locus
• Other a-specific gene expression is default
• Driven by MCM1 homodimer
• MAT? gene expression
• ?1, ?2 mRNA from MAT?
• ?1 and ?2 function
• Repress a-specific genes
• ?2/MCM1 heterodimer
• Stimulate ?-specific genes
• ?1/MCM1 heterodimer

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Mating Type Specific Gene Expression
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Mating Type Switch Mechanism HO
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Mating Type Switch Mechanism hetero-sequence
switch
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Recombination Enhancer Sequence
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Sequence-Specific RE Effects
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RE Sequence Shows MatAlpha2 Binding Site
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RE Mutants Render Chromatin Structural Change
wt

mt

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A Mcm1p Binding Site in RE is Necessary for RE
Function
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MatAlpha2 Interaction with Tup1/Ssn6 is Essential
for Haploid/a-specific Gene Repression
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Tup1/Ssn6 Complex is Global Transcription
Suppressor Associated with HDACs
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A Model Summarizing Mcm1p-Mediated Chromosomal
Effects on RE and Other Loci
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Evolution of the Molecular Logic of Mating Type
in Fungi
S.Pombe
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Maternal Effect on Mating Type Switch
???
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HO Promoter Dissection
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HO Expression Depends on Swi/Snf Complex LOF and
GOF
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Ash1p Represses Mating Type Switch in Daughter
Cell by Inhibiting HO Expression
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Ash1p and Swi/Snf Show Reciprocal Effects on
Mating Type Switch
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Ash1p Localization Dependence Genetic Screen
Screen for mother cells who do NOT express HO
(promoter is inhibited) as a consequence of any
genetic defect
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She Genes are Necessary for HO Expression
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She1p/5p are Cytoskeletal Proteins, and Some She
Genes are Localized to Daughter Cells
Interdependence of She genes on localization
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Actin-dependent Ash1 mRNA Localization into
Daughter Cell
Pharmacology LOF
FISH
Genetics GOF
Genetics LOF
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She genes and Ash1 mRNP transport
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Visualizing mRNA Transport
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Local Translation
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Local Translation Regulation is as Essential as
Localization
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Protein Level in Temporal Context
Degredation for old alpha2 as well as HO etc
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Protein Dynamics not Limited to Ash1 mRNA
Transportation