Lectures in University of Brawijaya, 2013 Biological Responses to Environmental Stress Tetsuro Ishii, PhD. Professor Emeritus, University of Tsukuba, Japan

Animal Plant poisons Detoxification system Natural immunity Repair system Apoptosis 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 synthesis Repair damages Cell damages Acquire tolerance Activation of transcription factors Heat shock Oxidative stress HSFs Nrf2

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 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 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)

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