Acetylation of lysine residues in the recombinant nucleoprotein and VP40 matrix protein of Zaire Ebolavirus by eukaryotic histone acetyltransferases.

Acetylation of histones and other proteins plays crucial roles in transcriptional regulation, chromatin organization, and other biological processes. It has been recently reported that the nucleoprotein (NP) of influenza virus is acetylated in infected cells, and this modification contributes to the RNA polymerization activity of the virus. As the influenza virus, the Ebolavirus contains single-stranded negative-sense RNA as its viral genome, which interacts with NP and other viral proteins. In this study, we performed a series of biochemical experiments and revealed that the recombinant Ebolavirus NP and the viral matrix protein VP40, which binds with NP, were acetylated by eukaryotic histone acetyltransferases, such as P300/CREB-binding protein (P300/CBP) and P300/CBP-associated factor (PCAF), in vitro. Mass spectrometry was used to identify the lysine residues that were potential acetylation targets in NP and VP40. The identified lysine residues in NP were located in the RNA-binding cleft and the VP35-binding domain. Potentially acetylated lysine targets in VP40 were identified in the basic patch, which is necessary for constructing oligomers. These results suggest that the acetylation of these lysine residues is involved in the interactions between viral proteins.

Organocatalytic Enantioselective Nucleophilic Alkynylation of Allyl Fluorides Affording Chiral Skipped Ene-ynes.

Asymmetric methods for preparation of chiral alkynyl-containing compounds are in extremely high demand in many sectors of chemical research. In this work, we report the discovery of a general organocatalytic enantioselective alkynylation based on the idea of Si/F activation of the allylic C-F bond. This approach features reasonably broad substrate scope, functional group tolerance, and relatively neutral, mild, and operationally convenient reaction conditions; all of which bode well for the synthetic value of the discovered method. In particular, this method provides unique chiral skipped 1,4-ene-ynes having two kinds of versatile functional groups.

Enhancing Diabetes Management for Older Patients: The Potential Role of ChatGPT.

Artificial intelligence (AI) technology has the potential to improve diabetes education for older individuals with diabetes. However, as AI becomes integrated into healthcare, it will be important to ensure even greater accuracy and establish a framework. The significance of direct communication between patients and healthcare providers will remain unchanged, regardless of the level of technological advancement.

Comprehensive molecular motion capture for sphingomyelin by site-specific deuterium labeling.

Lipid rafts have attracted much attention because of their significant functional roles in membrane-associated processes. It is thought that sphingomyelin and cholesterol are essential for forming lipid rafts; however, their motion characteristics are not fully understood despite numerous studies. Here we show accurate local motions encompassing an entire sphingomyelin molecule, which were captured by measuring quadrupole splittings for 19 kinds of site-specifically deuterated sphingomyelins (that is, molecular motion capture of sphingomyelin). The quadrupole splitting profiles, which are distinct from those reported from perdeuterated sphingomyelins or simulation studies, reveal that cholesterol enhances the order in the middle parts of the alkyl chains more efficaciously than at the shallow positions. Comparison with dimyristoylphosphocholine bilayers suggests that cholesterol is deeper in sphingomyelin bilayers, which likely explains the so-called umbrella effect. The experiments also demonstrate that (i) the C2'-C3' bond predominantly takes the gauche conformation, (ii) the net ordering effect of cholesterol in sphingomyelin bilayers is not larger than that in phosphatidylcholine bilayers, (iii) cholesterol has no specific preference for the acyl or sphingosine chain, (iv) the acyl and sphingosine chains seem mismatched by about two methylene lengths, and (v) the motion of the upper regions of sphingomyelin chains is less temperature dependent than that of lower regions probably due to intermolecular hydrogen bond formation among SM molecules. These insights into the atomic-level dynamics of sphingomyelin provide critical clues to understanding the mechanism of raft formation.

Design and synthesis of sphingomyelin-cholesterol conjugates and their formation of ordered membranes.

A lipid raft is a cholesterol (Chol)-rich microdomain floating in a sea of lipid bilayers. Although Chol is thought to interact preferentially with sphingolipids such as sphingomyelin (SM), rather than with glycerophospholipids, the origin of the specific interaction has remained unresolved, primarily because of the high mobility of lipid molecules and weak intermolecular interactions. In this study, we synthesized SM-Chol conjugates with functionally designed linker portions to restrain Chol mobility and examined their formation of ordered membranes by a detergent insolubility assay, fluorescence anisotropy experiments, and fluorescence-quenching assay. In all of the tests, membranes prepared from the conjugates showed properties of ordered domains comparable to a SM-Chol (1:1) membrane. To gain insight into the structure of bilayers composed from the conjugates, we performed molecular dynamics simulations with 64 molecules of the conjugates, which suggested that the conjugates form a stable bilayer structure by bending at the linker portion and, mostly, reproduce the hydrogen bonds between the SM and Chol portions. These results imply that the molecular recognition between SM and Chol in an ordered domain is essentially reproduced by the conjugated molecules and, thus, demonstrates that these conjugate molecules could potentially serve as molecular probes for understanding molecular recognition in lipid rafts.

Vasorelaxant effects of macrocyclic bis(bibenzyls) from liverworts.

Vasorelaxant effects of a series of bis(bibenzyls) from liverworts such as Marchantia polymorpha and Marchantia paleacea on rat aorta demonstrated that they relaxed phenylephrine (PE)-induced contractions, which may be mediated through the increased release of NO from endothelial cells as well as opening of K(+) channels, and inhibition of Ca(2+) influx through voltage-dependent Ca(2+) channels (VDCs) and/or receptor-operated Ca(2+) channels (ROCs). Structure-activity relationship based on their structures was discussed. The presence of two aromatic rings which can be connected through two atoms bridge spacer may play an important role for vasorelaxant effect.

Using 1 HN amide temperature coefficients to define intrinsically disordered regions: An alternative NMR method.

This report describes a cost-effective experimental method for determining an intrinsically disordered protein (IDP) region in a given protein sample. In this area, the most popular (and conventional) means is using the amide (1 HN ) NMR signal chemical shift distributed in the range of 7.5-8.5 ppm. For this study, we applied an additional step: analysis of 1 HN chemical shift temperature coefficients (1 HN -CSTCs) of the signals. We measured 1 H-15 N two-dimensional NMR spectra of model IDP samples and ordered samples at four temperatures (288, 293, 298, and 303 K). We derived the 1 HN -CSTC threshold deviation, which gives the best correlation of ordered and disordered regions among the proteins examined (below -3.6 ppb/K). By combining these criteria with the newly optimized chemical shift range (7.8-8.5 ppm), the ratios of both true positive and true negative were improved by approximately 19% (62-81%) compared with the conventional "chemical shift-only" method.

Efficient method for the deprotection of tert-butyldimethylsilyl ethers with TiCl4-Lewis base complexes: application to the synthesis of 1beta-methylcarbapenems.

TiCl4-Lewis base (AcOEt, CH3NO2) complexes smoothly deprotected tert-butyldimethylsilyl (TBDMS) ethers. The reaction velocity with these complexes, which seemed less reactive due to the influence of Lewis bases, was considerably greater than that with TiCl4 alone. Selective desilylations between aliphatic and aromatic TBDMS ethers (1 and 5), between 1 and benzyl, allyl, tosyl, methoxyphenyl, and chloroacetyl ethers (13, 14, 15, 16, and 17), and between TBDMS and TBDPS ethers (18 and 19) were successfully performed. Desilylation of TBDMS-aldol, acyloin, and beta-lactam analogues 9-12 proceeded smoothly due to anchimeric assistance by the neighboring carbonyl groups. The present method was successfully applied to the practical synthesis of 1beta-methylcarbapenems 20a'-f'.