lab of industrial microbiology, korea university 2010010566 hyeon jeong eun

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Lab of Industrial Microbiology, Korea university 2010010566 Hyeon Jeong Eun

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Lab of Industrial Microbiology, Korea university 2010010566 Hyeon Jeong Eun. Introduction. Adhesion & Flocculation. One of the most critical functions of the cell surface Prevents cells from being washed away Allows them to form biofilms that offer protection ability. - PowerPoint PPT Presentation

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Page 1: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

Lab of Industrial Microbiology, Korea university2010010566

Hyeon Jeong Eun

Page 2: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

Introduction• Adhesion & Flocculation- One of the most critical functions of the cell surface- Prevents cells from being washed away- Allows them to form biofilms that offer protection ability

Fungal (Yeast) Adhesion 1) Adhere to abiotic surfaces such as plastic 2) Cell-Cell adhesion ( Flocculation )

=>Phenotypic variability and plasticity

Page 3: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

Introduction

• Biofilm- A complex aggregation of microorganisms marked by the excretion of a protective and adhesive matrix

Medical and industrial relevance of fungal adhesion

1) The remarkable plasticity -> New drugs

2) Separate biomass from various fermentation products

-J. Valle et al., “Broad-spectrum biofilm inhibition by a secreted bacterial polysaccharide,” PNAS 103(33): 12558-12563. 2006.

Page 4: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Adhesins or Flocculins ; Specialized cell-surface proteins

- Bind specific amino acid or sugar residues

A common three-domain structure

1) C-terminal : Glycosylphosphatidylinositol (GPI)-anchor

2) N-terminal : Carbohydrate or peptide binding domain

3) Middle domain

: Multiple serine and

threonine-rich repeats

Page 5: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Fig1. Secretion and cell-surface anchoring of fungal adhesins

Page 6: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• FigS1. Phylogenetic tree of cellular adhesins and mucins

Page 7: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Fig2. Cell-cell and cell-surface adhesion associated with the S. cerevisiae FLO genes

[1] Expresses the FLO1

[2] Does not express any FLO gene

[3] Overexpresses FLO11

Page 8: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Different of mechanisms of adhesion

1) Lectin-like adhesion (sugar sensitive)• N-terminus : lectin-like carbohydrate binding domain• Two sub-categories - Flo1 group : only binds mannose sugars - NewFlo group : binds various sugars

2) Sugar-insensitive adhesion• bind peptides or increase the cell-surface hydrophobicity

Page 9: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Controlled by several signaling pathways- Triggered by certain stress factors and/or nutrient limitation

FLO11-mediated cell-surface adhesion 1) Ras-cAMP pathway 2) MAP kinase-dependent filamentous growth pathway 3) The main glucose repression pathway

( not yet known ) 4) Target of Rapamycin (TOR) pathway – nitrogen starvation 5) Transcription factors Sok2, Phd1, Adh1 – Epistatic pathway

Page 10: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Fig3A. The MAPK-dependent filamentous growth pathway

Ste11, Ste7: Central kinase

Msb2 : mucin-like transmembrane protein

Mep2: Ammonium permease

Page 11: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Fig3B. The Ras/cAMP/PKA pathway

Cyr1: adenylate cyclase

PKA: Protein kinase A complex

Sfl1: Suppressor of flocculation

Page 12: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Fig3B. The main glucose repression pathway

Hxt: Hexose transporters

Hxk: Hexokinases

Sfl1: Suppressor of flocculation

Page 13: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Controlled epigenetically

1) Cells regulary switch between the states ( transcribed <-> silent )

2) Stochastic switching mechanism ( Nonsense mutation )

3) Chromatin remodeling

Goals of adhesins silencing

1) Balance between adhering, colonizing cells and non-adhering cells

2) Proactively anticipate new conditions in fluctuating environments

3) Allowing them to adhere to specific surfaces only

4) Different subsets may allow evasion of the host immune system

Page 14: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Recombination of Intragenic repeats ; Novel adhesins

- Fastest expanding group of paralogues in the genomes

The driving force behind the creation of novel adhesins

1) Trigger frequent slippage, recombination events - Longer adhesins generally confer greater adherence

2) Recombination events between repeats of different genes - Generate chimeirc forms

Page 15: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Fig4. Box plot of the S. cerevisiae FLO1 nucleotide sequence

Page 16: Lab of Industrial Microbiology, Korea university 2010010566  Hyeon Jeong Eun

• Fungal adhesion is an unusually complex and variable phenotype

1) Quickly adapt their adhesive properties to a particular environments

2) Many different genetic and epigenetic signaling cascades

3) The internal tandem repeats trigger frequent recombination events

• For Industrial applications,

the instability of the flocculation profile is a true nightmare

Recombinant DNA techniques

• For Medical applications,

the remarkable plasticity of fungal adhesion also causes concern

Targets for new drugs

Conclusion