Heat stress response in plants: a complex game with chaperones and more than twenty heat stress transcription factors.
Compared to the overall multiplicity of more than 20 plant Hsfs, detailed analyses are mainly restricted to tomato and Arabidopsis and to three important representatives of the family (Hsfs A1, A2 and B1). The three Hsfs represent examples of striking functional diversification specialized for the three phases of the heat stress (hs) response (triggering, maintenance and recovery). This is best illustrated for the tomato Hsf system: (i) HsfA1a is the master regulator responsible for hs-induced gene expression including synthesis of HsfA2 and HsfB1. It is indispensible for the development of thermotolerance. (ii) Although functionally equivalent to HsfA1a, HsfA2 is exclusively found after hs induction and represents the dominant Hsf, the "working horse" of the hs response in plants subjected to repeated cycles of hs and recovery in a hot summer period. Tomato HsfA2 is tightly integrated into a network of interacting proteins (HsfA1a, Hsp17-CII, Hsp17-CI) influencing its activity and intracellular distribution. (iii) Because of structural peculiarities, HsfB1 acts as coregulator enhancing the activity of HsfA1a and/or HsfA2. But in addition, it cooperates with yet to be identified other transcription factors in maintaining and/or restoring housekeeping gene expression.
Baniwal
Sanjeev Kumar
SK
Department of Molecular Cell Biology, Goethe University Frankfurt, Marie Curie Str. 9, D-60439 Frankfurt/M., Germany.
Bharti
Kapil
K
Chan
Kwan Yu
KY
Fauth
Markus
M
Ganguli
Arnab
A
Kotak
Sachin
S
Mishra
Shravan Kumar
SK
Nover
Lutz
L
Port
Markus
M
Scharf
Klaus-Dieter
KD
Tripp
Joanna
J
Weber
Christian
C
Zielinski
Dirk
D
von Koskull-Döring
Pascal
P
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins; D015139:Blotting, Southern; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D006361:Heating; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C000620134:HSFA2 protein, Arabidopsis; C000620135:HSFB1 protein, Arabidopsis; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D010940:Plant Proteins; D014157:Transcription Factors