There is growing evidence that metabolic enzymes may act as multifunctional proteins performing diverse roles in cellular metabolism. Among these functions are the RNA-binding activities of NAD+-dependent dehydrogenases. Previously, we have chartacterized the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an RNA-binding protein with preference to adenine-uracil-rich sequences. In this study, we used GST-GAPDH fusion proteins generated by deletion mutagenesis to search for the RNA binding domain. We established that the N-terminal 43 amino acid residues of GAPDH, which correspond to the first mononucleotide-binding domain of the NAD+-binding fold is sufficient to confer RNA-binding. We also provide evidence that this single domain, although it retains most of the RNA-binding activity, loses sequence specificity. Our results suggest a molecular basis for RNA-recognition by NAD+-dependent dehydrogenases and (di)nucleotide-binding metabolic enzymes that had been reported to have RNA-binding activity with different specificity. To support this prediction we also identified other members of the family of NAD+-dependent dehydrogenases with no previous history of nucleic acid binding as RNA binding proteins in vitro. Based on our findings we propose the addition of the NAD+-binding domain to the list of RNA binding domains/motifs. (C) 2000 Academic Press.
|Number of pages||8|
|Journal||Biochemical and biophysical research communications|
|Publication status||Published - Aug 28 2000|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology