The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Mutagenesis of bacterial elongation factor Tu at lysine 136. A conserved amino acid in GTP regulatory proteins.

We have studied the effects of specific amino acid replacements in EF-Tu upon the protein's interactions with guanine nucleotides and elongation factor Ts (EFTs). We found that alterations at the lysine residue of the Asn-Lys-Cys-Asp sequence, the guanine ring-binding sequence, differentially affect the protein's ability to bind guanine nucleotides. Wild type EF-Tu (Lys-136) binds GDP and GTP much more tightly than do many of the altered proteins. Replacing lysine by arginine lowers the protein's affinity for GDP by about 20-fold relative to the change in its affinity for EF-Ts. Substitutions at residue 136 by glutamine (K136Q) and glutamic acid (K136E) further lower the protein relative affinity for GDP by factors of about 4 and 10, respectively. In contrast, replacement of the residue by isoleucine (K136I) eliminates guanine nucleotide binding as well as EF-Ts binding. Apparently, the distortion of this loop by substitution at residue 136 of a bulky hydrophobic residue can hamper the binding for both substrates or disrupt the folding of the protein. All altered proteins except EF-Tu(K136I) are able to bind tRNA(Phe); however, they require much higher concentrations of GTP than wild type EF-Tu. In minimal media, Escherichia coli cells harboring plasmids encoding EF-Tu(K136E) or EF-Tu(K136Q) suffer growth retardation relative to cells bearing the same plasmid encoding wild type EF-Tu. Co-transformation of these cells with a compatible plasmid bearing the EF-Ts gene reverses this growth problem. The growth retardation effect of some of the altered proteins can be explained by their sequestering EF-Ts. These results indicate that EF-Ts is essential to the growth of E. coli and suggest a technique for studying EF-Ts mutants as well as for identifying other guanine nucleotide exchange enzymes.[1]


WikiGenes - Universities