ClpB/Hsp100 proteins and heat stress tolerance in plants

Abstract

High-temperature stress can disrupt cellular proteostasis, resulting in the accumulation of insoluble protein aggregates. For survival under stressful conditions, it is important for cells to maintain a pool of native soluble proteins by preventing and/or dissociating these aggregates. Chaperones such as GroEL/GroES (Hsp60/Hsp10) and DnaK/DnaJ/GrpE (Hsp70/Hsp40/nucleotide exchange factor) help cells minimize protein aggregation. Protein disaggregation is accomplished by chaperones belonging to the Caseinolytic Protease (Clp) family of proteins. ClpB/Hsp100 proteins are strikingly ubiquitous and are found in bacteria, yeast and multi-cellular plants. The expression of these proteins is regulated by heat stress (HS) and developmental cues. Bacteria and yeast contain one and two forms of ClpB proteins, respectively. Plants possess multiple forms of these proteins that are localized to different cellular compartments (i.e. cytoplasm/nucleus, chloroplast or mitochondria). Overwhelming evidence suggests that ClpB/Hsp100 proteins play decisive roles in cell adaptation to HS. Mutant bacteria and yeast cells lacking active ClpB/Hsp100 proteins are critically sensitive to high-temperature stress. Likewise, Arabidopsis, maize and rice mutants lacking cytoplasmic ClpB proteins are very sensitive to heat. In this study, we present the structural and functional attributes of plant ClpB forms.

• Bacteria
• chaperone
• heat stress
• heat shock protein
• Hsp100
• plants
• proteostasis
• rice
• thermotolerance
• yeast

Declaration of interest

The authors report no declarations of interest. RCM acknowledges the Council of Scientific and Industrial Research (CSIR) and the Government of India, New Delhi, for the Fellowship award. AG is thankful to the Centre for Advanced Research and Innovation on Plant Stress and Development Biology, the Department of Biotechnology (DBT), the Government of India and J.C.Bose Fellowship award grant, the Department of Science and Technology (DST), and the Government of India for financial support.

Supplementary material available online

Supplementary Tables S1-S2 and Figures S1-S2.