Crystal structure of cce_0566 from Cyanothece 51142, a protein associated with nitrogen fixation in the DUF269 family

The crystal structure for cce_0566 (171 aa, 19.4 kDa), a DUF269 annotated protein from the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142, was determined to 1.60 Å resolution. Cce_0566 is a homodimer with each molecule composed of eight α-helices folded on one side of a three strand anti-parallel β-sheet. Hydrophobic interactions between the side chains of largely conserved residues on the surface of each β-sheet hold the dimer together. The fold observed for cce_0566 may be unique to proteins in the DUF269 family, hence, the protein may also have a function unique to nitrogen fixation. A solvent accessible cleft containing conserved charged residues near the dimer interface could represent the active site or ligand-binding surface for the protein’s biological function.Structured summary of protein interactionsDUF269 and DUF269bind by x-ray crystallography (View interaction)

► First structural characterization of a protein from the DUF269 family. ► Dali search indicates protein fold is unique in current protein space. ► Homodimer with each unit containing 8 α-helices and 3-strand anti-parallel β-sheet. ► Hydrophobic interactions between intermolecular β-sheets hold dimer together. ► Cleft containing conserved charged residues at dimer interface is possible active site.