Nucleotide-binding flexibility in ultrahigh-resolution structures of the SRP GTPase Ffh.

ABSTRACT: Two structures of the nucleotide-bound NG domain of Ffh, the GTPase subunit of the bacterial signal recognition particle (SRP), have been determined at ultrahigh resolution in similar crystal forms. One is GDP-bound and one is GMPPCP-bound. The asymmetric unit of each structure contains two protein monomers, each of which exhibits differences in nucleotide-binding conformation and occupancy. The GDP-bound Ffh NG exhibits two binding conformations in one monomer but not the other and the GMPPCP-bound protein exhibits full occupancy of the nucleotide in one monomer but only partial occupancy in the other. Thus, under the same solution conditions, each crystal reveals multiple binding states that suggest that even when nucleotide is bound its position in the Ffh NG active site is dynamic. Som

SUBMITTER: Ramirez UD 

PROVIDER: S-EPMC2631121 | biostudies-literature | 2008 Oct

REPOSITORIES: biostudies-literature