ctcf is the main architectural protein found in most of the examined bilaterian organisms. the cluster of the C2H2 zinc-finger domains involved in recognition of long DNA-binding motif is only part of the protein that is evolutionarily conserved, while the N-terminal domain (NTD) has different sequences. Here, we performed biophysical characterization of CTCF NTDs from various species representing all major phylogenetic clades of higher metazoans. With the exception of Drosophilides, the N-terminal domains of CTCFs show an unstructured organization and absence of folded regions in vitro. In contrast, NTDs of Drosophila melanogaster and virilis ctcfs contain unstructured folded regions that form tetramers and dimers correspondingly in vitro. Unexpectedly, most NTDs are able to self-associate in the yeast two-hybrid and co-immunoprecipitation assays. These results suggest that NTDs of CTCFs might contribute to the organization of ctcf-mediated long-distance interactions and chromosomal architecture. Chromosomes in the genomes of all higher eukaryotes have a highly organized architecture and consist of discrete topologically associated domains (TADs) 1-5. TADs often also include smaller domains (sub-TADs) that are flanked by short boundary elements or longer regions (inter-TADs) that contain active chromatin and housekeeping genes. In addition, promoters, enhancers, silencers and insulators form a network of specific distance interactions that properly regulate gene transcription 6-9. Until now, the unresolved question remains how specific distance interactions between remote regulatory elements are established and maintained through the cell cycle 10. Currently, the best-characterized protein involved in the organization of chromosome architecture is CTCF, which was initially found as a transcriptional repressor 11. It is believed that CTCF is the main architectural protein in mammals, which is responsible for the organization of TAD boundaries and distance interactions between enhancers and promoters 12-16. CTCF was found in most of the higher eukaryotes including all studied bilateral organisms but is absent in yeast and plants 17,18. Usually CTCFs from different organisms contain the cluster of eleven C2H2 zinc-finger domains (ZF) localized in the central part of the protein. In human CTCF, ZFs from 3 to 7 recognize specific 15 bp consensus 19. The DNA-binding ZFs are the most evolutionary conserved among CTCFs that bind to similar sites in most higher eukaryotic genomes 20. Moreover, it was found that even several chromatin domains controlled by CTCF are conserved in distant species 21. Other ZF domains are usually less conserved

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A series of cyclometalated Ru(II) complexes with 2-arylbenzimidazoles antenna ligands bearing electron-donor/withdrawing substituents and anchoring 4,4′-dimethoxycarbonyl-2,2′-bipyridine have been prepared and their structure, optical and electrochemical properties have been studied. The...

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Williams-Beuren syndrome is a genetic disorder characterized by physiological and mental abnormalities, and is caused by hemizygous deletion of several genes in chromosome 7. One of the removed genes encodes the WBSCR27 protein. Bioinformatic analysis of the sequence of WBSCR27 indicates that it belongs to the family of SAM-dependent methyltransferases. However, exact cellular functions of this protein or phenotypic consequences of its deficiency are still unknown. Here we report nearly complete H,N, and C chemical shifts assignments of the 26 kDa WBSCR27 protein from Mus musculus in complex with the cofactor S-adenosyl-L-methionine (SAM). Analysis of the assigned chemical shifts allowed us to characterize the protein's secondary structure and backbone dynamics. The topology of the protein's fold confirms the assumption that the WBSCR27 protein belongs to the family of class I methyltransferases.

Transcriptional regulators select their targets from a large pool of similar genomic sites. The binding of the Drosophila dosage compensation complex (DCC) exclusively to the male X chromosome provides insight into binding site selectivity rules. Previous studies showed that the male-specific organizer of the complex, MSL2, and ubiquitous DNA-binding protein CLAMP directly interact and play an important role in the specificity of X chromosome binding. Here, we studied the highly specific interaction between the intrinsically disordered region of MSL2 and the N-terminal zinc-finger C2H2-type (C2H2) domain of CLAMP. We obtained the NMR structure of the CLAMP N-terminal C2H2 zinc finger, which has a classic C2H2 zinc-finger fold with a rather unusual distribution of residues typically used in DNA recognition. Substitutions of residues in this C2H2 domain had the same effect on the viability of males and females, suggesting that it plays a general role in CLAMP activity. The N-terminal C2H2 domain of CLAMP is highly conserved in insects. However, the MSL2 region involved in the interaction is conserved only within the Drosophila genus, suggesting that this interaction emerged during the evolution of a mechanism for the specific recruitment of the DCC on the male X chromosome in Drosophilidae.

Background: Ionizing Radiation (IR) is one of the major limiting factors for human deep-space missions. Preventing IR-induced cognitive alterations in astronauts is a critical success factor. It has been shown that cognitive alterations in rodents can be inferred by alterations of a psycho- emotional balance, primarily an anxiogenic effect of IR. In our recent work, we hypothesized that the neurokinin-1 (NK1) receptor might be instrumental for such alterations. Objective: The NK1 receptor antagonist rolapitant and the classic anxiolytic diazepam (as a comparison drug) were selected to test this hypothesis on Wistar rats. Method: Pharmacological substances were administered through intragastric probes. We used a battery of tests for a comprehensive ethological analysis. High-performance liquid chromatography was applied to quantify monoamines content. An analysis of mRNA expression was performed by real-time PCR. Protein content was studied by the Western blotting technique. Results: Our salient finding includes no substantial changes in anxiety, locomotor activity and cognitive abilities of treated rats under irradiation. No differences were found in the content of monoamines. We discovered a synchronous effect on mRNA expression and protein content of 5- HT2a and 5-HT4 receptors in the prefrontal cortex, as well as decreased content of serotonin transporter and increased content of tryptophan hydroxylase in the hypothalamus of irradiated rats. Rolapitant affected the protein amount of a number of serotonin receptors in the amygdala of irradiated rats. Conclusion : Rolapitant may be the first atypical radioprotector, providing symptomatic treatment of CNS functional disorders in astronauts caused by IR.

Williams-Beuren syndrome, characterized by numerous physiological and mental problems, is caused by the heterozygous deletion of chromosome region 7q11.23, which results in the disappearance of 26 protein-coding genes. Protein WBSCR27 is a product of one of these genes whose biological function has not yet been established and for which structural information has been absent until now. Using NMR, we investigated the structural and functional properties of murine WBSCR27. For protein in the apo form and in a complex with S-(5 0-adenosyl)-L-homocysteine (SAH), a complete NMR resonance assignment has been obtained and the secondary structure has been determined. This information allows us to attribute WBSCR27 to Class I methyltransferases. The interaction of WBSCR27 with the cofactor S-(5 0-adenosyl)-L-methionine (SAM) and its metabolic products-SAH, 5 0-deoxy-5 0-methylthioadenosine (MTA) and 5 0-deoxyadenosine (5 0 dAdo)was studied by NMR and isothermal titration calorimetry. SAH binds WBSCR27 much tighter than SAM, leaving open the question of cofactor turnover in the methylation reaction. One possible answer to this question is the presence of weak but detectable nucleosidase activity for WBSCR27. We found that the enzyme catalyses the cleavage of the adenine moiety from SAH, MTA and 5 0 dAdo, similar to the action of bacterial SAH/MTA nucleosidases. We also found that the binding of SAM or SAH causes a significant change in the structure of WBSCR27 and in the conformational mobility of the protein fragments, which can be attributed to the substrate recognition site. This indicates that the binding of the cofactor modulates the folding of the substrate-recognizing region of the enzyme.