Characterization of Atypical Protein Tyrosine Kinase (PTK) Genes and Their Role in Abiotic Stress Response in Rice.

Allimuthu Elangovan,Lekshmy Sathee,Gopinathan Kumar Krishna,Monika Dalal,Viswanathan Chinnusamy,Sellathdurai Devika,Ranjeet Ranjan Kumar

doi:10.3390/plants9050664

Abstract

Tyrosine phosphorylation constitutes up to 5% of the total phophoproteome. However, only limited studies are available on protein tyrosine kinases (PTKs) that catalyze protein tyrosine phosphorylation in plants. In this study, domain analysis of the 27 annotated PTK genes in rice genome led to the identification of 18 PTKs with tyrosine kinase domain. The kinase domain of rice PTKs shared high homology with that of dual specificity kinase BRASSINOSTEROID-INSENSITIVE 1 (BRI1) of Arabidopsis. In phylogenetic analysis, rice PTKs clustered with receptor-like cytoplasmic kinases-VII (RLCKs-VII) of Arabidopsis. mRNAseq analysis using Genevestigator revealed that rice PTKs except PTK9 and PTK16 express at moderate to high level in most tissues. PTK16 expression was highly abundant in panicle at flowering stage. mRNAseq data analysis led to the identification of drought, heat, salt, and submergence stress regulated PTK genes in rice. PTK14 was upregulated under all stresses. qRT-PCR analysis also showed that all PTKs except PTK10 were significantly upregulated in root under osmotic stress. Tissue specificity and abiotic stress mediated differential regulation of PTKs suggest their potential role in development and stress response of rice. The candidate dual specificity PTKs identified in this study paves way for molecular analysis of tyrosine phosphorylation in rice.

Highlights

Protein kinases catalyze phosphorylation of serine (Ser), threonine (Thr), and tyrosine (Tyr) residue of target proteins by transferring the γ-phosphate from ATP
Analysis of 27 annotated putative protein tyrosine kinases (PTKs) in rice genome led to the identification 18 PTKs with protein tyrosine kinase motif
The kinase domains of PTKs showed high homology with that of Arabidopsis BRASSINOSTEROID-INSENSITIVE 1 (BRI1), a well characterized dual specific kinase, suggesting that the 18 PTKs identified in this study are dual specific kinases

Summary

Introduction

Protein kinases catalyze phosphorylation of serine (Ser), threonine (Thr), and tyrosine (Tyr) residue of target proteins by transferring the γ-phosphate from ATP. Based on their substrate specificity to phosphorylate Ser/Thr and Tyr residues, protein kinases were initially classified into Ser/Thr kinases and Tyr kinases, respectively [1]. Serine phosphorylation (pS) is most common followed by threonine (pT) and tyrosine phosphorylation (pY) In plants such as rice and Arabidopsis, the relative abundance of pS and pT is about 80–85% and 10–15%, respectively, while pY ranges between 0–5% [3,4,5].

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Conclusion