Protein folding is an essential step for protein functionality. In eukaryotes this process is carried out by multiple chaperones that act in a cooperative manner to maintain the proteome homeostasis. Some of these chaperones are assisted during protein folding by different co-chaperones. One of these co-chaperones is HOP, the HSP70-HSP90 organizing protein. HOP co-chaperone, due to its importance, has been deeply analyzed in other eukaryotes, but its function has only recently started to be envisaged in plants. In this article, researchers from the Center for Plant Biotechnology and Genomics (CBGP-UPM / INIA) have analyzed the role of HOP in response to different environmental and cellular conditions such as heat stress, pathogen attack or endoplasmic reticulum (ER) stress. This analysis reveals that HOP is an important regulator of stress responses that course with an accumulation of misfolded proteins and with an overwhelming of the folding machinery. This research highlights the role of HOP in the folding of proteins, either to reach their native structure or to maintain proteins in an intermediate folding state while they reach their final destination or while they bind to key co-factors for their functionality. This research also indicates that, depending on the conditions, HOP proteins could be involved in the massive folding of proteins or in the selective folding of specific proteins. Furthermore, this research identifies HOP orthologues in different plant species and analyzes the specificity of different members of the Arabidopsis HOP family in response to different environmental conditions.
Toribio, R., Mangano, S., Fernández-Bautista, N., Muñoz, A., Castellano, M.M. 2020. HOP, a Co-chaperone Involved in Response to Stress in Plants. Frontiers in Plant Science 11, 1657. DOI: 10.3389/fpls.2020.591940