Identification of a type II cystatin in Fragaria chiloensis: A proteinase inhibitor differentially regulated during achene development and in response to biotic stress-related stimuli

• Published in: Plant physiology and biochemistry Vol. 129; pp. 158 - 167
• Main Authors: Aceituno-Valenzuela, Uri, Covarrubias, María Paz, Aguayo, María Francisca, Valenzuela-Riffo, Felipe, Espinoza, Analía, Gaete-Eastman, Carlos, Herrera, Raúl, Handford, Michael, Norambuena, Lorena
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.08.2018
• Subjects: Cystatin; Cystatins - metabolism; Cystatins - physiology; Cysteine Endopeptidases - metabolism; Escherichia coli; Fragaria - metabolism; Fragaria - physiology; Fragaria chiloensis; Fruit - growth & development; Fruit - metabolism; Fruit - physiology; Fruit development; Microorganisms, Genetically-Modified; Papain - metabolism; Phytocystatin; Plant Proteins - metabolism; Plant Proteins - physiology; Stress; Stress, Physiological; Transcriptome; Fragaria chiloensis; Cystatin; Fruit development; Phytocystatin; Stress
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2018.05.021

The equilibrium between protein synthesis and degradation is key to maintaining efficiency in different physiological processes. The proteinase inhibitor cystatin regulates protease activities in different developmental and physiological contexts. Here we describe for the first time the identification and the biological function of the cysteine protease inhibitor cystatin of Fragaria chiloensis, FchCYS1. Based on primary sequence and 3D-structural homology modelling, FchCYS1 is a type II phytocystatin with high identity to other cystatins of the Fragaria genus. Both the papain-like and the legumain-like protease inhibitory domains are indeed functional, based on in vitro assays performed with Escherichia coli protein extracts containing recombinant FchCYS1. FchCYS1 is differentially-expressed in achenes of F. chiloensis fruits, with highest expression as the fruit reaches the ripened stage, suggesting a role in preventing degradation of storage proteins that will nourish the embryo during seed germination. Furthermore, FchCYS1 responds transcriptionally to the application of salicylic acid and to mechanical injury, strongly suggesting that FchCYS1 could be involved in the response against pathogen attack. Overall these results point to a role for FchCYS1 in diverse physiological processes in F. chiloensis. •A type II cystatin structurally similar to phytocystatins was identified.•FchCYS1 possesses inhibitory activity over both proteases papain and legumain.•FchCYS1 is regulated in achene development and responds to biotic-related stress.