The Arabidopsis Aminopeptidase LAP2 Regulates Plant Growth, Leaf Longivity and Stress Response

ABSTRACT: Peptidases are known to play key roles in multiple biological processes in all living organisms. In a model plant Arabidopsis, the vast majority of many putative aminopeptidases remain uncharacterized. We therefore aim to explore physiological function of uncharacterized aminopeptidase in higher plants using Arabidopsis as a model to study.We performed functional and expression analyses of the Arabidopsis LAP2 through cDNA cloning, isolation of T-DNA insertional mutants, characterization of the enzymatic activity, characterization of gene expression, and transcriptomic and metabolomic analyses of the mutants. We found that LAP2, one of the 28 aminopeptidases in Arabidopsis, regulates plant growth, leaf longevity and stress response by controlling intracellular protein turnover. Loss-of-function alleles of LAP2 reduced in vegetative growth, accelerated leaf senescence and rendered plants more sensitive to various stresses. LAP2 is highly expressed in the quiescent center cells in the root meristem, cotyledons and leaf veins. Integration of global gene expression and metabolite analyses suggest that LAP2 controlled intracellular protein turnover. The mutant maintained free leucine by up-regulating key genes for leucine biosynthesis, however, this influenced the flux of glutamate strikingly. As a result, gamma-aminobutyric acid, a metabolite which is derived from glutamate, was diminished in the mutant. Decrements in these nitrogen-rich compounds are associated with morphological alterations and stress sensitivity of the mutant.Our results provide molecular and biochemical evidence that LAP2 is indeed an enzymatically active aminopeptidase. LAP2 plays key roles in senescence, stress response and protein turnover. Regulated proteolysis is an important mechanism in all stages of the plant life cycle. The present study would contribute to further understanding of the aminopeptidases which have several implications in higher plants.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE22000 | GEO | 2010/06/02

SECONDARY ACCESSION(S): PRJNA127225

REPOSITORIES: GEO