Brachypodium distachyon ERECTA-like1 protein kinase is a functional guanylyl cyclase.

Brygida Świeżawska ,Klaudia Hammer ,Maria Duszyn ,Aloysius Wong ,Adriana Szmidt-Jaworska ,Krzysztof Jaworski

doi:10.52586/e882

Abstract

The plant proteins called ERECTA family play important role in inflorescence architecture, stomatal patterning and phloem-xylem organization. ERECTA proteins belong to the moonlighting proteins family containing the guanylyl cyclase (GC) catalytic center embedded within the intracellular kinase domain. This characteristic architecture of ERECTA proteins prompted us to experimentally confirm of enzymatic activity of one of these, BdERL1 (ERECTA-like1 from Brachypodium distachyon). We have shown that BdERL1 is dual-function protein with both kinase and GC activity. Moreover, our mutagenesis studies also revealed the catalytic roles of key conserved amino acid residues at the GC center and importantly, probing of the kinase and GC with Ca2+ and/or cGMP, shed light on the intramolecular regulations of BdERL1.

Highlights

Based on bioinformatics prediction of the GCPred tool, the BdERL1 protein was identified as a potential new guanylyl cyclase harboring a conserved GC motif that is localized within the cytosolic C-terminus of the studied protein (BdERL1 GC center840−853) [21]
The GC motif present within BdERL1 [840SFGIVLLELLTGKK-853] possesses all three highly conserved functional amino acids localized at positions 1, 3 and 14 (Fig. 1A), where serine at position 1 forms a hydrogen bond with guanine, glycine at position 3 confers substrate specificity for GTP and lysine at position 14 stabilizes the transition state from GTP to cGMP
Bioinformatics analysis of the amino acid sequence of BdERL1 revealed that the calmodulin-binding site is localized within the kinase domain of the protein and did not show the presence of the EF hand motif (Fig. 1B)

Summary

Objectives

The purpose of our study was to establish the moonlighting function of the GC in BdERL1 and to determine the catalytic roles of the two functionally assigned and highly conserved amino acids at positions 3 and 14 within the GC catalytic center of BdERL1, as well as to investigate how a functional GC in BdERL1 might affect its kinase activity

Methods

Results

Conclusion