Interaction of cellular nucleic acid binding protein (CNBP) with putative cellular targets.

CALCATERRA, N. B.; ARMAS, P.

Bariloche, Argentina.

Congreso; Bariloche Protein Symposium - Argentine Society for Biochemistry and Molecular Biology (SAIB) - XXXIX Annual Meeting. Biophysical Society of Argentina (SAB) - XXXII Annual Meeting.; 2003

Argentine Society for Biochemistry and Molecular Biology (SAIB) - Biophysical Society of Argentina (SAB).

CNBP was identified as a cellular factor that interacts with single-stranded nucleic acids. It has been related to many mechanisms of gene expression regulation ranging from transcription to translation. However, its biological function reminds unknown. By band-shift assays we analysed the ability of CNBP and different mutant CNBP forms to interact with single-stranded nucleic acid probes (RNA and DNA from 5’-UTR of L4-ribosomal protein mRNA) in order to identify protein motifs involved in the interaction. We show that (i) an RGG motif is the most committed with the protein binding to RNA targets, but not to targets of DNA with the same sequence; (ii) the interaction with RNA, but not with DNA, requires addition of embryonic factors; and (iii) CNBP interacts with DNA as a monomer as well as a dimmer whereas its binding to RNA is mainly as a dimmer. This implies a differential mechanism of CNBP interaction with each kind of single stranded nucleic acids.For defining whether CNBP has a regulative action in c-myc proto-oncogen expression we tested CNBP interaction with several c-myc putative regulatory sequences. Only the 5’-UTR of c-myc mRNA showed interaction following a binding pattern similar to that of L4-5’UTR. This suggests that CNBP may not be restricted to bind ribosomal protein mRNAs and could act in a more generalised mechanism of translational control.