A NMR guided approach for CsrA–RNA crystallization

Abstract

Structure determination of protein–nucleic acid complexes remains a challenging task. Here we present a simple method for generating crystals of a CsrA–nucleic acid complex, guided entirely by results from nuclear magnetic resonances spectroscopy (NMR) spectroscopy. Using a construct that lacks thirteen non-essential C-terminal residues, efficient binding to DNA could be demonstrated. One CsrA dimer interacts with two DNA oligonucleotides, similar to previous findings with RNA. Furthermore, the NMR study of the CsrA–DNA complex was the basis for successfully homing in on conditions that were suitable for obtaining crystals of theCsrA–DNAcomplex.Our resultsmay be useful for those caseswhereRNAin protein–nucleic acid complexes may be replaced by DNA.