RESUMO
Eukaryotic and archaeal translation initiation factor 2 in complex with GTP delivers the initiator methionyl-tRNA to the small ribosomal subunit. Over the past 20 years, thanks to the efforts of various research groups, including ours, this factor from the archaeon Sulfolobus solfataricus and its individual subunits have been crystallized in ten different space groups. Analysis of the molecular packing in these crystals makes it possible to better understand the roles of functionally significant switches and other elements of the nucleotide-binding pocket during the function of the factor as well as the influence of external effects on its transition between active and inactive states.
Assuntos
Proteínas Arqueais , Sulfolobus solfataricus , Sulfolobus solfataricus/química , Sulfolobus solfataricus/metabolismo , Proteínas Arqueais/química , Proteínas Arqueais/metabolismo , Cristalografia por Raios X , Modelos Moleculares , Guanosina Trifosfato/metabolismo , Guanosina Trifosfato/química , Fatores de Iniciação de Peptídeos/química , Fatores de Iniciação de Peptídeos/metabolismo , Conformação Proteica , Sítios de Ligação , RNA de Transferência de Metionina/química , RNA de Transferência de Metionina/metabolismoRESUMO
Protein synthesis on ribosomes is considered the main process in cell life. Regulation of ribosomal protein gene expression plays an important role in the balanced synthesis of proteins and RNA in ribosomal biogenesis. This review is focused on some features of autoregulation of ribosomal protein synthesis in prokaryotes. Inhibition of the synthesis of ribosomal proteins encoded by 12 operons by mechanisms of competition , "entrapment", and retroregulation are discussed. Examples of regulation of protein synthesis by individual ribosomal proteins and their complexes are presented.
Assuntos
Escherichia coli , Biossíntese de Proteínas , Escherichia coli/genética , Óperon , RNA Ribossômico/metabolismo , Proteínas Ribossômicas/genética , Ribossomos/genética , Ribossomos/metabolismoRESUMO
The conserved two-domain ribosomal protein (r-protein) L1 is a structural part of the L1 stalk of the large ribosomal subunit and regulates the translation of the operon that comprises its own gene. The regulatory properties of the bacterial r-protein L1 have only been studied in detail for Escherichia coli; however, there were no such studies for other bacteria, in particular, Thermus thermophilus and Thermotoga maritima, which are more evolutionarily ancient. It is known that domain I of the r-protein L1 might have regulatory properties of the whole protein. The aim of this study was to identify regulatory sites on the mRNA of T. thermophilus and T. maritima that interact with r-proteins L1, as well as with their domains I from the same organisms. An analysis of the mRNA of the L11 operon T. thermophilus showed the presence of one potential binding site of the L1 r-protein, two such regions were found also in the mRNA sequence of the L11 operon of T. maritima. The dissociation constants for the L1 proteins from T. thermophilus and T. maritima and their domains I with mRNA fragments from the same organisms that contain the supposed L1-binding sites were determined by surface plasmon resonance. It has been shown that the ribosomal proteins L1 as their domains I bind specific fragments of mRNA from the same organisms that may suggest regulatory activity of the L1 protein in the T. thermophilus and T. maritima and conservatism of the principles of L1-RNA interactions.
