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Lectures in University of Brawijaya, 2013 Biological Responses to Environmental Stress Tetsuro Ishii, PhD. Professor Emeritus, University of Tsukuba, Japan. Animals have developed defense system against environmental stress agents. Plant. Animal. poisons. Detoxification system

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Lectures in University of Brawijaya, 2013

Biological Responses to Environmental Stress

Tetsuro Ishii, PhD.

Professor Emeritus, University of Tsukuba, Japan


Animals have developed defense system against environmental stress agents

Plant

Animal

poisons

Detoxification system

Natural immunity

Repair system

Apoptosis

Toxic agents

UV, As, Heavy metals

Infection

Bacteria, Virus


Stress causes upregulation of stress proteins stress agents

Detection by sensors

stressor

Cell damages

Activation of transcription factors

Heat shock

Oxidative stress

HSFs

Nrf2

Acquire tolerance

Gene activation

Protein synthesis

Repair damages


Biological Responses to Environmental Stress stress agents

1. Cellular response to heat

2. Cellular response to electrophiles and reactive oxygen species

3. Nrf2 target genes


Heat was necessary to create life stress agents

Hydrothermal vent

Yellowstone hot spring

Adaptation to heat is most important for life.


Heat shock induces various proteins in cells stress agents

Temperature shift

43°C

37°C

Activation of heat shock factors

Induction of heat shock proteins (HSPs)

Has60, Hsp70, Hsp90, etc.


Heat shock protein (HSP) family stress agents

HSP110

HSP100

HSP90

HSP70 (DNAK)

HSP60 (chaperonin, GroEL)

HSP47

HSP40 (DNAJ)

HSP33

HSP27

HSP15

HSP10

Some of these proteins are constitutively expressed and play their roles under normal temperature.


Some proteins return to native form following heat denaturation

denature or unfolding

Renature or refolding

But, many proteins became aggregated when denatured


Denatured/unfolded proteins tend to aggregate denaturation

Protein aggregates


Inhibition of protein aggregation by Dank-ClpB denaturation

Heat shock

Aggregation

Native form


Chaperonin inhibits protein aggregation denaturation

albumin

Native form

Urea + DTT

Denatured form

Enzyme activity

turbidity

± chaperonin


ATP-dependent folding of GFP-protein by chaperonin denaturation

GFP fluorescence

Time (min)

(-) chaperonin

Inhibition of protein aggregate by chaperonin

Opitical Scattering

(+) chaperonin

Time (min)


Chaperonin inhibits protein aggregate by heat treatment denaturation

Without chaperonin

With chaperonin




Discovery of chaperonin denaturation

“Molecular chaperon” was found in different systems


Functions of chaperonin during protein synthesis denaturation

Protein synthesis

hsp

Miss-folding

chaperonin

aggregates

normal folding




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