ABSTRACT
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.
Subject(s)
Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Ribosomal Proteins/chemistry , Ribosomal Proteins/genetics , Amino Acid Sequence , Crystallography, X-Ray , Methanococcus/metabolism , Molecular Sequence Data , Mutation , Protein Conformation , Thermus thermophilus/metabolismABSTRACT
It is shown within the framework of stereochemical modeling that disruption of water shells of proteins and nucleic acids is confronted by significant kinetic barriers caused by the breaking of hydrogen bonds. The structure of the water shells is dictated by the surface of proteins and nucleic acids, therefore the kinetic barriers due to disruption of the water shell are strongly distinct from each other on different parts of the shell. This, in turn, means that the probability of participation of different parts of the protein and nucleic acid surfaces in intermolecular interactions should be varied through a wide range, i.e. the water shell should strengthen selectivity of molecular recognition.
