Identification of a Coding Sequence and Structure Modeling of a Glycine-Rich RNA-Binding Protein (CmGRP1) from Chelidonium majus L.

The family of glycine-rich plant proteins (GRPs) is a large and complex group of proteins that share, as a common feature, the presence of glycine-rich domains arranged in (Gly)n-X repeats that are suggested to be involved in protein–protein interactions, RNA binding, and nucleolar targeting. These proteins are implicated in several independent physiological processes. Some are components of cell walls of many higher plants, while others are involved in molecular responses to environmental stress, and mediated by post-transcriptional regulatory mechanisms. The goals of this study are to identify the coding sequence of a novel glycine-rich RNA-binding protein from Chelidonium majus and to propose its structural model. DNA fragments obtained using degenerate PCR primers showed high sequence identities with glycine-rich RNA-binding protein coding sequences from different plant species. A 439-bp nucleotide sequence is identified coding for a novel polypeptide composed of 146 amino acids, designated as CmGRP1 (C. majus glycine-rich protein 1), with a calculated MW of 14,931 Da (NCBI GenBank accession no. HM173636). Using NCBI CDD and GeneSilico MetaServer, a single conserved domain, the RNA recognition motif (RRM), was detected in CmGRP1. The C-terminal region of CmGRP1 is a glycine-rich motif (GGGGxxGxGGGxxG), and it is predicted to be disordered. Based on a 1fxl crystal structure, a 3D model of CmGRP1 is proposed. CmGRP1 can be classified as a class IVa plant GRP, implicated to play a role in plant defense.