The N‑Terminal T–T Motif of a Third-Generation HIV‑1 Fusion Inhibitor Is Not Required for Binding Affinity and Antiviral Activity

The highlighted next-generation HIV-1 fusion inhibitor peptide <b>1</b> is capped by two threonines. Here, we generated peptide <b>2</b> by deleting the T–T motif and compared their structural and antiviral properties. Significantly, two peptides showed similar helical and oligomeric states in solution, comparable binding affinities to the target, and no significant difference to inhibit HIV-1 fusion and infection. Also, the T–T motif was not associated with peptide <b>1</b> resistant mutations and its deletion did not affect peptide <b>1</b> against enfuvirtide-resistant HIV-1 mutants. The redundancy of the T–T motif was further verified by the model peptide C34 and short peptide inhibitors that mainly target the gp41 pocket, suggesting that the N-terminal T–T motif of peptide <b>1</b> could be removed or modified toward the development of new anti-HIV-1 drugs. Consistently, our data have verified that the M–T hook structure rather than the T–T motif is an efficient strategy for short peptide fusion inhibitors

Internal Electric Field Assisted Photocatalytic Generation of Hydrogen Peroxide over BiOCl with HCOOH

Hydrogen peroxide (H₂O₂) is a superb, clean, and versatile reagent. However, large-scale production of H₂O₂ is manufactured through nongreen methods that motivate people to develop more efficient and green technologies as alternatives. As a novel and green technology used for H₂O₂ generation, the efficiency of photocatalysis is still far from satisfactory. Here, we demonstrate a novel and efficient path of the generation of H₂O₂ in BiOCl photocatalysis but not the direct electron reduction of O₂ or hole oxidation of OH^– to H₂O₂. Super high production (685 μmol/h) of H₂O₂ by the addition of HCOOH as the hole shuttle was realized over BiOCl nanoplates. In this photocatalytic system, the BiOCl supplied abundant photoinduced holes to initiate HCOO^• radical. The HCOO^• further reacts with OH^– to •OH which is proven to be the source of the H₂O₂. Apart from HCOOH, O₂ also played important roles. The O₂ not only promoted the reaction through the cycle between Bi³⁺ and Bi, which decreased the combination of carriers, but also avoided the carbonation of surfaces, thus achieving the high production of H₂O₂ (1020 μmol/h). In this work, we shed light on a deep understanding of the photocatalytic evolution of H₂O₂ in a novel perspective and achieve high production

Positive and negative effects of graphite flake and monolayer graphene oxide templates on protein crystallization

Heterogeneous template-induced nucleation is a promising way to regulate protein crystallization events and could be employed for purification processes and crystallographic studies. Protein crystallization process with graphite and graphene oxide, as heterogeneous templates, were investigated. More than 640 hanging drops with different concentrations of Lysozyme (30, 50, 70, 100 mg/mL) and NaCl (0.7, 0.9, 1.1, 1.3, 1.5 M) were crystallised at 4 °C with or without graphite/graphene oxide templates. The induction times and crystallization process were observed under the microscope. The lysozyme in the solutions with graphite flakes nucleated faster under all the conditions than the lysozyme with equal experimental conditions without templates. The crystals preferred to grow around the edge of graphite flakes than on the flat surfaces. In the droplets with monolayer graphene oxide, more crystals appeared around graphene oxide particles, and the faster or slower nucleation processes with templates were dependent on the lysozyme and NaCl concentrations. Graphene oxide templates strongly inhibited nucleation at high lysozyme concentrations but promoted nucleation at low lysozyme concentrations. Both heterogeneous templates changed the crystal morphology and the crystallization kinetics. More crystals were observed in the solution with graphite templatesthan with graphene oxide templates and without any template

Western blot analysis of Hsp3101, Hsp3102, Hsp3105 and Sdj1 in wild-type, Δ<i>sty1</i> and Δ<i>atf1</i> cells.

<p>Wild-type, Δ<i>sty1</i> and Δ<i>atf1</i> cells were grown in YES medium. Cell lysates were prepared, and proteins were separated by SDS/PAGE and analyzed by immunoblotting with indicated antibodies. Sla1 serves as the loading control.</p

Deletion of <i>hsp31</i> and <i>sdj1</i> genes affects subcellular localization of GFP-Atg8.

<p>(A) GFP-Atg8 localization in wild type and deletion mutants of <i>hsp31</i> and <i>sdj1</i>. Cells were grown in YES medium and analyzed by fluorescence microscopy. Samples were taken at indicated time points during growth. (B) Quantitative analysis of the GFP-Atg8 puncta in the panel (A) (mean ± SEM; n>500 cells). Statistical significance (*P < 0.05) was determined by Student's <i>t</i> test.</p

Induction of <i>S</i>. <i>pombe</i> homologs of DJ-1.

<p>(A) qRT-PCR analysis of expression of <i>S</i>. <i>pombe hsp3101-hsp3105</i> and <i>sdj1</i> genes in the wild-type cells. Total RNA was isolated from the wild-type cells grown in YES medium at the indicated time points. All mRNA levels were normalized to the control <i>act1</i>⁺ mRNA level and were expressed as fold change relative to the mRNA levels at the 7 h time point, which was set at a value of 1. Data are presented as mean ± SD (<i>p</i> ≤0.01; <i>t</i> test). (B) Immunoblot analyses of Hsp3101, Hsp3102, Hsp3105 and Sdj1 expression in wild-type cells. Crude extracts were prepared from the wild-type cells at indicated time points (h). Total proteins were separated on SDS/PAGE gels and immunoblotted using anti-Hsp3101 Ab, anti- Sdj1 Ab, anti-Myc Ab, which detects Hsp3102-Myc and Hsp3105-Myc, and anti-Sla1 Ab (serves as a loading control).</p

<i>Schizosaccharomyces pombe</i> Homologs of Human DJ-1 Are Stationary Phase-Associated Proteins That Are Involved in Autophagy and Oxidative Stress Resistance

<div><p>The Parkinson′s disease protein DJ-1 is involved in various cellular functions including detoxification of dicarbonyl compounds, autophagy and oxidative stress response. DJ-1 homologs are widely found in both prokaryotes and eukaryotes, constituting a superfamily of proteins that appear to be involved in stress response. <i>Schizosaccharomyces pombe</i> contains six DJ-1 homologs, designated Hsp3101-Hsp3105 and Sdj1 (previously named SpDJ-1). Here we show that deletion of any one of these six genes somehow affects autophagy during prolonged stationary phase. Furthermore, deletions of each of these DJ-1 homologs result in reduced stationary phase survival. Deletion of <i>sdj1</i> also increases the sensitivity of stationary-phase cells to oxidative stress induced by hydrogen peroxide (H₂O₂) whereas overexpression of <i>sdj1</i> has the opposite effect. Consistent with their role in stationary phase, expression of <i>hsp3101</i>, <i>hsp3102</i>, <i>hsp3105</i> and <i>sdj1</i>, and to a lesser extent <i>hsp3103</i> and <i>hsp3104</i>, is increased in stationary phase. The induction of <i>hsp3101</i>, <i>hsp3102</i>, <i>hsp3105</i> and <i>sdj1</i> involves the Sty1-regulated transcription factor Atf1 but not the transcription factor Pap1. Our results firmly establish that <i>S</i>. <i>pombe</i> homologs of DJ-1 are stationary-phase associated proteins and are likely involved in autophagy and antioxidant defense in stationary phase of <i>S</i>. <i>pombe</i> cells.</p></div

Loss of <i>hsp3102</i>, <i>hsp3104</i>, <i>hsp3105</i> and <i>sdj1</i> leads to delay of autophagy during stationary phase.

<p><i>S</i>. <i>pombe</i> cells expressing CFP-Atg8 were grown in YES medium and harvested at logarithmic phase (LP) (A) and prolonged stationary phase (SP) (B-D). (E) Deletion of <i>atg5</i> abolished CFP-Atg8 processing. Cells were lysed by sodium hydroxide and cell-free lysates were analyzed by immunoblotting using antibodies against GFP and Sla1 (loading control). The presence of free CFP is an indicator of autophagic flux.</p

Controlling Surface Termination and Facet Orientation in Cu₂O Nanoparticles for High Photocatalytic Activity: A Combined Experimental and Density Functional Theory Study

Cu₂O nanoparticles with controllable facets are of great significance for photocatalysis. In this work, the surface termination and facet orientation of Cu₂O nanoparticles are accurately tuned by adjusting the amount of hydroxylamine hydrochloride and surfactant. It is found that Cu₂O nanoparticles with Cu-terminated (110) or (111) surfaces show high photocatalytic activity, while other exposed facets show poor reactivity. Density functional theory simulations confirm that sodium dodecyl sulfate surfactant can lower the surface free energy of Cu-terminated surfaces, increase the density of exposed Cu atoms at the surfaces and thus benefit the photocatalytic activity. It also shows that the poor reactivity of the Cu-terminated Cu₂O (100) surface is due to the high energy barrier of holes at the surface region

List of <i>S</i>. <i>pombe</i> strains used in this study.

<p>List of <i>S</i>. <i>pombe</i> strains used in this study.</p