Hsp90-binding immunophilins in plants: the protein movers

Area of Science:

• Molecular Cell Biology
• Plant Biology
• Protein Trafficking

Background:

• Cytoplasmic-nuclear trafficking of the glucocorticoid receptor in mammalian cells involves the Hsp90/Hsp70 chaperone system and FKBP52.
• This machinery facilitates targeted movement of the receptor along microtubule tracts.
• Recent findings indicate that plant cells also possess analogous multiprotein chaperone systems.

Purpose of the Study:

• To investigate the presence and potential function of Hsp90/Hsp70-based chaperone machinery in plant cells.
• To explore the role of high molecular weight FKBP proteins in plant Hsp90 interactions.
• To determine if these conserved mechanisms are involved in targeting signaling protein trafficking in plants.

Main Methods:

• Comparative analysis of protein interaction domains, specifically tetratricopeptide repeat (TPR) domains.
• Biochemical assays to confirm binding between plant Hsp90 and high molecular weight FKBPs.
• Inference of functional roles based on conserved molecular mechanisms between mammalian and plant systems.

Main Results:

• Plant cells contain high molecular weight FKBP proteins that bind to plant Hsp90.
• This binding occurs via conserved protein interactions involving tetratricopeptide repeat domains.
• Evidence suggests a functional similarity to the mammalian Hsp90/Hsp70 chaperone system.

Conclusions:

• Plant cells utilize a multiprotein chaperone machinery, including Hsp90/Hsp70 systems and FKBPs, for protein trafficking.
• These conserved chaperone systems and FKBP proteins likely play a role in targeting signaling proteins in plants.
• This highlights conserved mechanisms for intracellular transport across different eukaryotic kingdoms.