Structure and function of the C-terminal domain of methionyl-tRNA synthetase.
The minimal polypeptide supporting full methionyl-tRNA synthetase (MetRS) activity is composed of four domains: a catalytic Rossmann fold, a connective peptide, a KMSKS domain, and a C-terminal alpha helix bundle domain. The minimal MetRS behaves as a monomer. In several species, MetRS is a homodimer because of a C-terminal domain appended to the core polypeptide. Upon truncation of this C-terminal domain, subunits dissociate irreversibly. Here, the C-terminal domain of dimeric MetRS from Pyrococcus abyssi was isolated and studied. It displays nonspecific tRNA-binding properties and has a crystalline structure closely resembling that of Trbp111, a dimeric tRNA-binding protein found in many bacteria and archaea. The obtained 3D model was used to direct mutations against dimerization of Escherichia coli MetRS. Comparison of the resulting mutants to native and C-truncated MetRS shows that the presence of the appended C-domain improves tRNA(Met) binding affinity. However, dimer formation is required to evidence the gain in affinity.
Crepin
Thibaut
T
Laboratoire de Biochimie, Unité Mixte de Recherche 7654, CNRS-Ecole Polytechnique, F-91128 Palaiseau Cedex, France.
Schmitt
Emmanuelle
E
Blanquet
Sylvain
S
Mechulam
Yves
Y
D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D007700:Kinetics; D008718:Methionine-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D021122:Protein Subunits; D019711:Pyrococcus / Q000201:enzymology / Q000235:genetics; D012329:RNA, Bacterial / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000138:chemical synthesis / Q000235:genetics; D013329:Structure-Activity Relationship
D019843:Archaeal Proteins; D010446:Peptide Fragments; D021122:Protein Subunits; D012329:RNA, Bacterial; D011994:Recombinant Proteins; D012343:RNA, Transfer; D008718:Methionine-tRNA Ligase