Role of cytosolic glutamyl-tRNA synthetase (GluRS) on the localization of chloroplastic proteins

• Grant number: 17/04396-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: September 01, 2017
• End date: October 31, 2020
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Principal Investigator: Márcio de Castro Silva Filho
• Grantee: Camila Fernandes Moro
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 14/50275-9 - Deciphering the molecular mechanisms involved in the localization of organelar proteins as well as the complex plant-insect-pathogen interactions, AP.BIOEN.TEM

Abstract

Chloroplasts and mitochondria are semi-autonomous organelles because they depend on the nuclear genome to encode their own set of proteins. Thus, it was essential to develop an accurate mechanism of protein import into these organelles. Protein targeting to mitochondria or chloroplasts involve distinct import machineries, which demonstrate a high level of targeting specificity. However, several physiological reactions may occur in more than one subcellular compartment, which in turn, request members of the same family of the protein to be translocated to more than one organelle. In these situations, a gene-duplication process took place during evolution. Usually, gene duplications were followed by acquisition of specific targeting sequences, which guaranteed proper destination of the organelar proteins. On the other hand, an increasing number of proteins encoded by single genes are requested in both organelles. These proteins are dual-targeted to mitochondria and chloroplasts in a coordinated manner. One of the best characterized dual-targeted protein families is the aminoacyl-t-RNA synthetases. These proteins are mainly associated with protein synthesis, but some studies have shown that this class of proteins may also participate in other events including the subcellular localization of proteins. Cytosolic glutamyl-tRNA synthetase (GluRS) is involved in subcellular localization of proteins in yeast and mammals and it seems that also performs this role in plants. Recent results in our lab have shown that cytosolic GluRS somehow regulates the subcellular localization of plastid proteins. However, the exact role of GluRS in the subcellular localization of proteins has not yet been determined. This is the first study that will provide the molecular basis involved in the functional expansion of GluRS in acting as a cytosolic factor in the subcellular localization of dual-target proteins that are essential for plant development.