Phosphorylation and subsequent interaction with 14-3-3 proteins regulate plastid glutamine synthetase in Medicago truncatula

• Tipo: Artigo em Revista Científica Internacional
• Data: 2006

Autores

lima, l (Autor) Outra; seabra, a (Autor) Outra; melo, p (Autor) FCUP; cullimore, j (Autor) Outra; carvalho, h (Autor) REIT

Revista

Título: Planta

Vol. 223

Páginas: 558-567

ISSN: 0032-0935

Editora: Springer Nature

Indexação

ISI Web of Knowledge - 47 Citações

Scopus - 52 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Ciências biológicas

Outras Informações

ID Authenticus: P-004-NK3

DOI: 10.1007/s00425-005-0097-8

Abstract (EN): In this report we demonstrate that plastid glutamine synthetase of Medicago truncatula (MtGS2) is regulated by phosphorylation and 14-3-3 interaction. To investigate regulatory aspects of GS2 phosphorylation, we have produced non-phosphorylated GS2 proteins by expressing the plant cDNA in E. coli and performed in vitro phosphorylation assays. The recombinant isoenzyme was phosphorylated by calcium dependent kinase(s) present in leaves, roots and nodules. Using an (His)(6)-tagged 14-3-3 protein column affinity purification method, we demonstrate that phosphorylated GS2 interacts with 14-3-3 proteins and that this interaction leads to selective proteolysis of the plastid located isoform, resulting in inactivation of the isoenzyme. By site directed mutagenesis we were able to identify a GS2 phosphorylation site (Ser97) crucial for the interaction with 14-3-3s. Phosphorylation of this target residue can be functionally mimicked by replacing Ser97 by Asp, indicating that the introduction of a negative charge contributes to the interaction with 14-3-3 proteins and subsequent specific proteolysis. Furthermore, we document that plant extracts contain protease activity that cleaves the GS2 protein only when it is bound to 14-3-3 proteins following either phosphorylation or mimicking of phosphorylation by Ser97Asp.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 10