Lectures in University of Brawijaya, 2013 Biological Responses to Environmental Stress Tetsuro Ishii, PhD. Professor Emeritus, University of Tsukuba, Japan
Jan 20, 2016
Lectures in University of Brawijaya, 2013
Biological Responses to Environmental Stress
Tetsuro Ishii, PhD.
Professor Emeritus, University of Tsukuba, Japan
Animal
Plant
poisons
Detoxification systemNatural immunityRepair systemApoptosis
Animals have developed defense system against environmental stress agents
Toxic agents
UV, As, Heavy metals
Infection
Bacteria, Virus
Stress causes upregulation of stress proteins
stressor Detection by sensors
Gene activation
Protein synthesisRepair damages
Cell damages
Acquire tolerance
Activation of transcription factors
Heat shockOxidative stress
HSFsNrf2
Biological Responses to Environmental Stress
1. Cellular response to heat
2. Cellular response to electrophiles and reactive oxygen species
3. Nrf2 target genes
Heat was necessary to create life
Adaptation to heat is most important for life.
Yellowstone hot spring
Hydrothermal vent
Heat shock induces various proteins in cells
37°C 43°C
Temperature shift
Induction of heat shock proteins (HSPs)Has60, Hsp70, Hsp90, etc.
Activation of heat shock factors
Heat shock protein (HSP) family
HSP110HSP100HSP90HSP70 (DNAK)HSP60 (chaperonin, GroEL)HSP47HSP40 (DNAJ)HSP33HSP27HSP15HSP10
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
Protein aggregates
Inhibition of protein aggregation by Dank-ClpB
Heat shock
Aggregation
Native form
Chaperonin inhibits protein aggregation
Native form
Denatured form
Urea + DTT
± chaperonin
albumin
Enzyme activity
turbidity
Opitical Scattering
Inhibition of protein aggregate by chaperonin
ATP-dependent folding of GFP-protein by chaperonin
GFP fluorescence
(+) chaperonin
(-) chaperonin
Time (min)
Time (min)
Without chaperonin
With chaperonin
Chaperonin inhibits protein aggregate by heat treatment
Double ring structure of chaperonin, GroEL
GroEL-GroES complex provides space for protein folding
Discovery of chaperonin
“Molecular chaperon” was found in different systems
Functions of chaperonin during protein synthesis
chaperonin
hsp
normal folding
aggregates
Protein synthesis
Miss-folding
Role of chaperons in protein synthesis
Role of chaperons in protein targeting to mitochondria