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Cullen Lecture 6: Signal Transduction in Fungi. Filamentous Growth Saccharomyces cerevisiae (G. Fink) And fungal pathogens.

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Presentation on theme: "Cullen Lecture 6: Signal Transduction in Fungi. Filamentous Growth Saccharomyces cerevisiae (G. Fink) And fungal pathogens."— Presentation transcript:

1 Cullen Lecture 6: Signal Transduction in Fungi

2 Filamentous Growth Saccharomyces cerevisiae (G. Fink) And fungal pathogens

3 Specificity of Signaling Pathways Containing Cdc42 and MAPK Components in Yeast

4 Signal Transduction Pathways Control Fungal Behavior StimulusResponse New Cell Type Signaling Cell Nucleus Receptor

5 FGP ? Cdc42/Ste20 Ste11 Ste7 Kss1 Ste12/Tec1 Filamentous Growth Pathway Receptor: GTPase/PAK: MAPK 3 : MAPK 2 : MAPK: Txn1/Txn2:

6 Yeast Signaling Proteins are Homologous to Mammalian Counterparts

7 http://www.hhmi.org/research/investigators/wu.html “Cross-Talk” in Signaling Pathways

8 Prediction of Specificity Factors Sho1 Ste20 42 ? Cell Wall Membrane FGP Sho1 + ? Cdc42/Ste20 Ste11 Ste7 Kss1 Ste12/Tec1

9 Characterize the Msb2 Protein Msb2 is glycosylated Msb2 is an Integral Membrane Protein

10 Msb2 Topology of Msb2 Cell Wall Plasma Membrane Glycosylated Integral Membrane Cell Surface

11 Ste20 42 Msb2 Sho1

12 Topology and Domain Structure of Msb2 Mucin-Homology Domain Signal Sequence Membrane- Spanning Domain 100 AA Extracellular Cytoplasmic Glycosylation Sites

13 Msb2 Msb2 is a Mucin Cell Wall Plasma Membrane Mucin- Homology Domain

14 Mucins are Gross but Important

15 Mucins in Mammalian Cells Disease resistance Metastasis Signaling role MUC1 and MUC4 Docks ß-catenin Grb2-Sos-Ras-MEK-ERK2 pathway Erb2/Her2/Neu Erb2-Erb3

16

17 Msb2’s Mucin-Homology Domain 100 AA N…(698)S Q V S D T S V S Y T T S S S S V S Q V S D T P V S Y T T S S S S V S Q V S D T S V P S T S S S S S V S Q V S D T P V P S T S S S S S V S Q (818) …C

18 wt  mucin Msb2 w/o the Mucin Domain is Hyperactive Is the Mucin Domain Required for FG Pathway Activity?

19 Mucin Repeats Are Inhibitory

20 Repeats are Homologous at the Nucleotide Level Undergo Recombination-Mediated Deletion Analysis of the Mucin Repeats (Continued)

21 Msb2-Dependence of MAPK Specificity PRP Receptor Fus3 FGP Msb2 Kss1

22 Msb2 induces Kss1~P but not Fus3~P

23

24 Conclusions Msb2 is a glycosylated integral-membrane cell-surface signaling mucin at the head of the FG pathway Msb2 is a FG pathway specific factor and part of the presumptive sensory complex Cdc42 and Sho1 are recruited to the FG pathway by Msb2 The mucin domain of Msb2 inhibits its function Msb2 is Secreted by the Exocyst Complex


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