RESUMO
Nine mutant forms of ribosomal proteins L1 from the bacterium Thermus thermophilus and the archaeon Methanococcus jannaschii were obtained. Their crystal structures were determined and analyzed. Earlier determined structure of S179C TthL1 was also thoroughly analyzed. Five from ten mutant proteins reveal essential changes of spatial structure caused by surface point mutation. It proves that for correct studies of biological processes by site-directed mutagenesis it is necessary to determine or at least to model spatial structures of mutant proteins. Detailed comparison of mutant L1 structures with that of corresponding wild type proteins reveals that side chain of a mutated amino acid residue tries to locate like the side chain of the original residue in the wild type protein. This observation helps to model the mutant structures.
Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas Ribossômicas/química , Proteínas Ribossômicas/genética , Sequência de Aminoácidos , Cristalografia por Raios X , Mathanococcus/metabolismo , Dados de Sequência Molecular , Mutação , Conformação Proteica , Thermus thermophilus/metabolismoRESUMO
Crystal structures of unbound protein L1 and of its complexes with ribosomal an messenger RNAs are analyzed. It is shown that the values of the apparent association rate constant for L1-RNA depend on conformation of unbound protein L1. It is suggested that L1 binds to rRNA with higher affinity than to mRNA because of additional interactions between domain II of L1 and the loop rRNA region, which is absent in mRNA.
