The structure of the cofactor-binding fragment of the LysR family member, CysB: a familiar fold with a surprising subunit arrangement

Abstract

The overall structure of CysB(88-324) is strikingly similar to those of the periplasmic substrate-binding proteins. A similar fold has also been observed in the cofactor-binding domain of Lac repressor, implying a structural relationship between the Lac repressor and LysR families of proteins. In contrast to Lac repressor, in CysB the twofold axis of symmetry that relates the monomers in the dimer is perpendicular rather than parallel to the long axis of the cofactor-binding domain. This seems likely to place the DNA-binding domains at opposite extremes of the molecule possibly accounting for CysB's extended DNA footprints.

Miscellaneous Algorithms for Density Modification

“…Examples of structure solutions using the dm program and a multi-crystal version include the GTPase-activating domain from p50rhoGAP (Barrett et al, 1997), and the cofactor-binding fragment of the LysR family member CysB (Tyrrell et al, 1998).…”

Functional Dissection of the LysR-type CysB Transcriptional Regulator

“…Knowing that WT CysB is a tetramer, the trans-dominance of the multicopy CysB mutant forms may be explained by titration of WT CysB monomers and formation of inactive mixed heterooligomers. Therefore, it seems that none of the mutations altering residues 11,20,22,160,196,244, and 247 abolished the oligomerization ability of CysB. In contrast, CysB variants E41K, L44R, and I48T expressed from plasmids did not confer the Cys Ϫ phenotype to the EC1250 strain and had no effect on expression of the cysBЈ::ЈlacZ fusion in the pMH303-containing EC1250 strain (Table II).…”

“…According to the structural model of the CysB dimer (20), 33 C-terminal amino acids (positions 292-324) form the loop exposed to the surface containing two helices. Therefore, this domain might be important for the overall structure of the native CysB molecule and its function.…”

“…This offers the tool for in vitro comparisons of properties of CysB mutants versus the wild-type protein. Second, the CysB protein is so far the only family member whose cofactor-binding domain (amino acids 88 -324) has been crystallized and subjected to three-dimensional analysis (20). The structure of the dimer formed by CysB monomer fragments (amino acids 88 -324) has shed some light on protein surfaces composing an inducer-and anti-inducer-binding cavity.…”

Purification, crystallization and preliminary X-ray diffraction analysis of the C-terminal fragment of the MvfR protein fromPseudomonas aeruginosa

“…They are composed of a DNA-binding domain and a cofactor-binding domain (Maddocks & Oyston, 2008). Several structures of proteins of the LysR family are known; the first structure to be reported was that of the cofactor-binding fragment of the CysB protein from Klebsiella aerogenes (Tyrrell et al, 1997), which revealed several similarities to structures of periplasmic substrate-binding proteins, although the subunit arrangement is different.…”