Structural and biochemical analysis of the Hordeum vulgare L. HvGR-RBP1 protein, a glycine-rich RNA-binding protein involved in the regulation of barley plant development and stress response

Biochemistry. 2014 Dec 23;53(50):7945-60. doi: 10.1021/bi5007223. Epub 2014 Dec 12.

Abstract

The timing of whole-plant senescence influences important agricultural traits such as yield and grain protein content. Post-transcriptional regulation by plant RNA-binding proteins is essential for proper control of gene expression, development, and stress responses. Here, we report the three-dimensional solution NMR structure and nucleic acid-binding properties of the barley glycine-rich RNA-binding protein HvGR-RBP1, whose transcript has been identified as being >45-fold up-regulated in early-as compared to late-senescing near-isogenic barley germplasm. NMR analysis reveals that HvGR-RBP1 is a multidomain protein comprising a well-folded N-terminal RNA Recognition Motif (RRM) and a structurally disordered C-terminal glycine-rich domain. Chemical shift differences observed in 2D (1)H-(15)N correlation (HSQC) NMR spectra of full-length HvGR-RBP1 and N-HvGR-RBP1 (RRM domain only) suggest that the two domains can interact both in-trans and intramolecularly, similar to what is observed in the tobacco NtGR-RBP1 protein. Further, we show that the RRM domain of HvGR-RBP1 binds single-stranded DNA nucleotide fragments containing the consensus nucleotide sequence 5'-TTCTGX-3' with low micromolar affinity in vitro. We also demonstrate that the C-terminal glycine-rich (HvGR) domain of Hv-GR-RBP1 can interact nonspecifically with ssRNA in vitro. Structural similarities with other plant glycine-rich RNA-binding proteins suggest that HvGR-RBP1 may be multifunctional. Based on gene expression analysis following cold stress in barley and E. coli growth studies following cold shock treatment, we conclude that HvGR-RBP1 functions in a manner similar to cold-shock proteins and harbors RNA chaperone activity. HvGR-RBP1 is therefore not only involved in the regulation of barley development including senescence, but also functions in plant responses to environmental stress.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cold-Shock Response / physiology*
  • DNA, Plant / chemistry
  • DNA, Plant / genetics
  • DNA, Plant / metabolism
  • DNA, Single-Stranded / chemistry
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism
  • Hordeum / genetics
  • Hordeum / metabolism*
  • Plant Proteins* / chemistry
  • Plant Proteins* / genetics
  • Plant Proteins* / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA, Plant / chemistry
  • RNA, Plant / genetics
  • RNA, Plant / metabolism
  • RNA-Binding Proteins* / chemistry
  • RNA-Binding Proteins* / genetics
  • RNA-Binding Proteins* / metabolism

Substances

  • DNA, Plant
  • DNA, Single-Stranded
  • Plant Proteins
  • RNA, Plant
  • RNA-Binding Proteins
  • grp3 protein, Hordeum vulgare

Grants and funding

National Institutes of Health, United States