A “Coiled-Coil” Motif Is Important for Oligomerization and DNA Binding Properties of Human Cytomegalovirus Protein UL77

Human cytomegalovirus (HCMV) UL77 gene encodes the essential protein UL77, its function is characterized in the present study. Immunoprecipitation identified monomeric and oligomeric pUL77 in HCMV infected cells. Immunostaining of purified virions and subviral fractions showed that pUL77 is a structural protein associated with capsids. In silico analysis revealed the presence of a coiled-coil motif (CCM) at the N-terminus of pUL77. Chemical cross-linking of either wild-type pUL77 or CCM deletion mutant (pUL77ΔCCM) implicated that CCM is critical for oligomerization of pUL77. Furthermore, co-immunoprecipitations of infected and transfected cells demonstrated that pUL77 interacts with the capsid-associated DNA packaging motor components, pUL56 and pUL104, as well as the major capsid protein. The ability of pUL77 to bind dsDNA was shown by an in vitro assay. Binding to certain DNA was further confirmed by an assay using biotinylated 36-, 250-, 500-, 1000-meric dsDNA and 966-meric HCMV-specific dsDNA designed for this study. The binding efficiency (BE) was determined by image processing program defining values above 1.0 as positive. While the BE of the pUL56 binding to the 36-mer bio-pac1 containing a packaging signal was 10.0±0.63, the one for pUL77 was only 0.2±0.03. In contrast to this observation the BE of pUL77 binding to bio-500 bp or bio-1000 bp was 2.2±0.41 and 4.9±0.71, respectively. By using pUL77ΔCCM it was demonstrated that this protein could not bind to dsDNA. These data indicated that pUL77 (i) could form homodimers, (ii) CCM of pUL77 is crucial for oligomerization and (iii) could bind to dsDNA in a sequence independent manner

Evolutionarily Conserved Herpesviral Protein Interaction Networks

Herpesviruses constitute a family of large DNA viruses widely spread in vertebrates and causing a variety of different diseases. They possess dsDNA genomes ranging from 120 to 240 kbp encoding between 70 to 170 open reading frames. We previously reported the protein interaction networks of two herpesviruses, varicella-zoster virus (VZV) and Kaposi's sarcoma-associated herpesvirus (KSHV). In this study, we systematically tested three additional herpesvirus species, herpes simplex virus 1 (HSV-1), murine cytomegalovirus and Epstein-Barr virus, for protein interactions in order to be able to perform a comparative analysis of all three herpesvirus subfamilies. We identified 735 interactions by genome-wide yeast-two-hybrid screens (Y2H), and, together with the interactomes of VZV and KSHV, included a total of 1,007 intraviral protein interactions in the analysis. Whereas a large number of interactions have not been reported previously, we were able to identify a core set of highly conserved protein interactions, like the interaction between HSV-1 UL33 with the nuclear egress proteins UL31/UL34. Interactions were conserved between orthologous proteins despite generally low sequence similarity, suggesting that function may be more conserved than sequence. By combining interactomes of different species we were able to systematically address the low coverage of the Y2H system and to extract biologically relevant interactions which were not evident from single species

Right handed chiral superstructures from achiral molecules: Self-assembly with a twist

The induction and development of chiral supramolecular structures from hierarchical self-assembly of achiral compounds is closely related to the evolution of life and the chiral amplification found in nature. Here we show that the combination of achiral tetraphenylethene (TPE) an AIE-active luminophore bearing four long alkyl chains via amide linkage allows the entire process of induction and control of supramolecular chirality into well-defined uniform right-handed twisted superstructures via solvent composition and polarity, i.e. solvophobic effect. We showed that the degree of twist and the pitch of the ribbons can be controlled to one-handed helical structure via solvophobic effects. The twisted superstructure assembly was visualised by scanning electron microscope (SEM) and transmission electron microscopy (TEM), furthermore, circular dichroism (CD) confirms used to determine controlled right-handed assembly. This controlled assembly of an AIE-active molecule can be of practical value; for example, as templates for helical crystallisation, catalysis and a chiral mechanochromic luminescent superstructure formation

The Supramolecular Self-Assembly of Aminoglycoside Antibiotics and their Applications

Aminoglycosides, a class of antibiotics that includes gentamicin, kanamycin, neomycin, streptomycin, tobramycin and apramycin, are derived from various streptomyces species. Despite the significant increase in the antibacterial resistant pathogens, aminoglycosides remain an important class of antimicrobial drugs due to their unique chemical structure which offers a broad spectrum of activity. The modification of antibiotics and their subsequent use in supramolecular chemistry is rarely reported. Given the importance of aminoglycosides, here we give a brief overview on the modification of 4,5- and 4,6-disubstituted deoxystreptamine classes of aminoglycosides through supramolecular chemistry and their potential for real world applications. We also make the case that the work in this area is gaining momentum, and there are significant opportunities to meet the challenges of modern antibiotics through the modification of aminoglycosides by harnessing the advantages of supramolecular chemistry

Supramolecular chemistry of AIE-active tetraphenylethylene luminophores

This book chapter provides recent progress in the development of chemistry of aggregation-induced emission (AIE)-active tetraphenylethylene luminophores, their synthetic strategies, and their applications in the research fields of optoelectronics, sensing and supramolecular science comprehensively. It begins with a discussion on a collection of synthetic structural motifs. We will also explore novel derivatives, structures, electronic and spectroscopic properties of the TPE luminophores. The practical applications include certain topics in medicinal, sensing, optoelectronic devices and supramolecular architectures. We have illustrated advances in tetraphenylethylene research in the mechanoluminescent materials followed by exploring recent development of functionalization/decoration of AIE-active tetraphenylethylene luminogens onto an aggregation-caused quenching (ACQ) fluorophores, such as PDI, NDI and porphyrins, converting the whole chromophore into AIE luminogens with possible applications

Precise aggregation-induced emission enhancement via H+ sensing and its use in ratiometric detection of intracellular pH values

A pyridyl functionalised tetraphenylethylene (Py-TPE) for ratiometric fluorescent detection of intracellular pH values is reported. The Py-TPE fluorescent probe can be used for H+ sensing in organic solvents (CHCl3, DMF and MeOH) and the change in optical density through absorption, emission and naked eye detection was modulated. On addition of TFA, an aggregation-induced enhancement of emission with an increase in quantum yield of 0.11 to 0.63, due to an intramolecular charge transfer (ICT) process was observed. This process is reversed by addition of TEA resulting in a cycle that can be repeated several times

Effect of amide hydrogen bonding interaction on supramolecular self-assembly of naphthalene diimide amphiphiles with aggregation induced emission

In the present work, two new naphthalene diimide (NDI) amphiphiles, NDI-N and NDI-NA, were successfully synthesized and employed to investigate their self-assembly and optical properties. For NDI-NA, which contains an amide group, aggregation-induced emission enhancement (AIEE) was demonstrated in the presence of various ratios of methylcyclohexane (MCH) in chloroform, which led to the visual color changes. This new amide-containing NDI-NA amphiphile formed nanobelt structures in chloroform/MCH (10:90, v/v) and microcup-like morphologies in chloroform/MCH (5:95, v/v). The closure of these microcups led to the formation of vesicles and microcapsules. The structural morphologies gained from the solvophobic control of NDI-NA were confirmed by various complementary techniques such as infrared spectroscopy, X-ray diffraction, and scanning and transmission electron microscopy. In the absence of the amide moiety in NDI-N, no self-assembly was observed, indicating the fundamental role of H-bonding in the self-association process

Xeroderma Pigmentosum C: A Valuable Tool to Decipher the Signaling Pathways in Skin Cancers

Xeroderma pigmentosum (XP) is a rare autosomal genodermatosis that manifests clinically with pronounced sensitivity to ultraviolet (UV) radiation and the high probability of the occurrence of different skin cancer types in XP patients. XP is mainly caused by mutations in XP-genes that are involved in the nucleotide excision repair (NER) pathway that functions in the removal of bulky DNA adducts. Besides, the aggregation of DNA lesions is a life-threatening event that might be a key for developing various mutations facilitating cancer appearance. One of the key players of NER is XPC that senses helical distortions found in damaged DNA. The majority of XPC gene mutations are nonsense, and some are missense leading either to the loss of XPC protein or to the expression of a truncated nonfunctional version. Given that no cure is yet available, XPC patients should be completely protected and isolated from all types of UV radiations (UVR). Although it is still poorly understood, the characterization of the proteomic signature of an XPC mutant is essential to identify mediators that could be targeted to prevent cancer development in XPC patients. Unraveling this proteomic signature is fundamental to decipher the signaling pathways affected by the loss of XPC expression following exposure to UVB radiation. In this review, we will focus on the signaling pathways disrupted in skin cancer, pathways modulating NER’s function, including XPC, to disclose signaling pathways associated with XPC loss and skin cancer occurrence