Search

This review summarizes the features of cold shock domain (CSD) proteins in the context of their interactions with nucleic acids and describes similarities and differences in the structure of cold shock proteins of prokaryotes and CSD proteins of eukaryotes with special emphasis on the functions related to the RNA/DNA-binding ability of these proteins. The mechanisms and specificity of their interaction with nucleic acids in relation to the growing complexity of protein domain structure are described, as well as various complexes of the mammalian Y-box binding protein 1 (YB-1) with nucleic acids (filaments, globules, toroids). The role of particular amino acid residues in the binding of nitrogenous bases and the sugar-phosphate backbone of nucleic acids is emphasized. The data on the nucleic acid sequences recognized by the Y-box binding proteins are systematized. Post-translational modifications of YB-1, especially its phosphorylation, affect the recognition of specific sequences in the promoter regions of various groups of genes by YB-1 protein. The data on the interaction of Lin28 protein with let-7 miRNAs are summarized. The features of the domain structure of plant CSD proteins and their effect on the interaction with nucleic acids are discussed.

This corrects the article DOI: 10.1134/S0006297917090012.

Formation of appropriate gut microbiota is essential for human health. The first two years of life is the critical period for this process. Selection of mutualistic microorganisms of the intestinal microbiota is controlled by the FUT2 and FUT3 genes that encode fucosyltransferases, enzymes responsible for the synthesis of fucosylated glycan structures of mucins and milk oligosaccharides. In this review, the mechanisms of the selection and maintenance of intestinal microorganisms that involve fucosylated oligosaccharides of breast milk and mucins of the newborn's intestine are described. Possible reasons for the use of fucose, and not sialic acid, as the major biological signal for the selection are also discussed.

Phosphonates are a class of organophosphorus compounds characterized by a chemically stable carbon-to-phosphorus (C-P) bond. Wide occurrence of phosphonates among xenobiotics polluting the environment has aroused interest in pathways and mechanisms of their biodegradation. Only procaryotic microorganisms and the lower eucaryotes are capable of phosphonate biodegradation via several pathways. Destruction of the non-activated C-P bond by the C-P lyase pathway is of fundamental importance, and understanding of the process is a basic problem of biochemistry and physiology of microorganisms. This review offers analysis of available data on phosphonate-degrading microorganisms, degradation pathways, and genetic and physiological regulation of this process.

The efficiency of secretion of Escherichia coli alkaline phosphatase depends on the presence in cells of a cytoplasmic chaperone--protein SecB. Secretion increases in the presence of this chaperone at 30 degrees C, which is the most favorable for the interaction of SecB with the export-initiation domain found previously in the N-terminal region of the mature enzyme. This interaction most likely occurs in the region of the export domain, which is located close to the signal peptide and in complex with a translocational ATPase--protein SecA.

The export signal has been assumed to be localized not only in the signal peptide of a secreted protein precursor, but also in the N-terminal region of the mature polypeptide chain. Mutant alkaline phosphatases with amino acid substitutions of two positively charged residues (Lys or Arg) in this region at different distances from the signal peptide have been studied to test this assumption. The efficiency of secretion has been shown to decrease in mutant proteins with amino acid substitutions in the region of 16-18 amino acid residues; the closer to the signal peptide is the substitution, the greater is the decrease. A change in the primary structure of the N-terminal domain results also in an increase in the Michaelis constant, which is greater the farther is the amino acid substitution from the signal peptide, suggesting a change in the enzyme function as well.

Thirteen investigated strains of ascomycetous yeasts able to produce secretory heat-shock proteins (sHSPs) do not response equally to a high temperature by induction of the synthesis and secretion of these proteins. In this respect the above yeasts can be divided into three groups having a positive (I), a negative (II), and an indefinite reaction (III) to the heat shock. The thermotolerant yeast Hansenula polymorpha belongs to the first group. In this yeast heat shock induces the synthesis and secretion of sHSP gp280. This new representative differs from known sHSPs in molecular mass and subunit composition. In other respects (glycosylation, mainly extracellular localization, and the character of export into the culture medium) it displays similar properties.