PMID:12705832
| Citation |
Nomura, T, Mochizuki, R, Dabbs, ER, Shimizu, Y, Ueda, T, Hachimori, A and Uchiumi, T (2003) A point mutation in ribosomal protein L7/L12 reduces its ability to form a compact dimer structure and to assemble into the GTPase center. Biochemistry 42:4691-8 |
|---|---|
| Abstract |
An Escherichia coli mutant, LL103, harboring a mutation (Ser15 to Phe) in ribosomal protein L7/L12 was isolated among revertants of a streptomycin-dependent strain. In the crystal structure of the L7/L12 dimer, residue 15 within the N-terminal domain contacts the C-terminal domain of the partner monomer. We tested effects of the mutation on molecular assembly by biochemical approaches. Gel electrophoretic analysis showed that the Phe15-L7/L12 variant had reduced ability in binding to L10, an effect enhanced in the presence of 0.05% of nonionic detergent. Mobility of Phe15-L7/L12 on gel containing the detergent was very low compared to the wild-type proteins, presumably because of an extended structural state of the mutant L7/L12. Ribosomes isolated from LL103 cells contained a reduced amount of L7/L12 and showed low levels (15-30% of wild-type ribosomes) of activities dependent on elongation factors and in translation of natural mRNA. The ribosomal activity was completely recovered by addition of an excess amount of Phe15-L7/L12 to the ribosomes, suggesting that the mutant L7/L12 exerts normal functions when bound on the ribosome. The interaction of Ser15 with the C-terminal domain of the partner molecule seems to contribute to formation of the compact dimer structure and its efficient assembly into the ribosomal GTPase center. We propose a model relating compact and elongated forms of L7/L12 dimers. Phe15-L7/L12 provides a new tool for studying the functional structure of the homodimer. |
| Links |
PubMed Online version:10.1021/bi027087g |
| Keywords |
Amino Acid Sequence; Dimerization; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/physiology; GTP Phosphohydrolases; Models, Molecular; Phenylalanine/genetics; Point Mutation; Protein Structure, Tertiary; Ribosomal Proteins/chemistry; Ribosomal Proteins/genetics; Ribosomal Proteins/physiology; Ribosomes/chemistry; Ribosomes/enzymology; Serine/genetics |
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