Enhanced Aromatic Sequons Increase Oligosaccharyltransferase Glycosylation Efficiency and Glycan Homogeneity

SummaryN-Glycosylation plays an important role in protein folding and function. Previous studies demonstrate that a phenylalanine residue introduced at the n-2 position relative to an Asn-Xxx-Thr/Ser N-glycosylation sequon increases the glycan occupancy of the sequon in insect cells. Here, we show that any aromatic residue at n-2 increases glycan occupancy in human cells and that this effect is dependent upon oligosaccharyltransferase substrate preferences rather than differences in other cellular processing events such as degradation or trafficking. Moreover, aromatic residues at n-2 alter glycan processing in the Golgi, producing proteins with less complex N-glycan structures. These results demonstrate that manipulating the sequence space surrounding N-glycosylation sequons is useful both for controlling glycosylation efficiency, thus enhancing glycan occupancy, and for influencing the N-glycan structures produced

Synthesis of Calcium(II) Amidinate Precursors for Atomic Layer Deposition through a Redox Reaction between Calcium and Amidines

Abstract We have prepared two new CaII amidinates, which comprise a new class of ALD precursors. The syntheses proceed by a direct reaction between Ca metal and the amidine ligands in the presence of ammonia. Bis(N,N′‐diisopropylformamidinato)calcium(II) (1) and bis(N,N′‐diisopropylacetamidinato)calcium(II) (2) adopt dimeric structures in solution and in the solid state. X‐ray crystallography revealed asymmetry in one of the bridging ligands to afford the structure [(η2‐L)Ca(μ‐η2:η2‐L)(μ‐η2:η1‐L)Ca(η2‐L)]. These amidinate complexes showed unprecedentedly high volatility as compared to the widely employed and commercially available CaII precursor, [Ca3(tmhd)6]. In CaS ALD with 1 and H2S, the ALD window was approximately two times wider and lower in temperature by about 150 °C than previously reported with [Ca3(tmhd)6] and H2S. Complexes 1 and 2, with their excellent volatility and thermal stability (up to at least 350 °C), are the first homoleptic CaII amidinates suitable for use as ALD precursors

Land use not litter quality is a stronger driver of decomposition in hyperdiverse tropical forest

Funded by Natural Environment Research Council. Grant Number: NE/K016253/1Peer reviewedPublisher PD

Coital frequency and condom use in monogamous and concurrent sexual relationships in Cape Town, South Africa

Introduction: A decreased frequency of unprotected sex during episodes of concurrent relationships may dramatically reduce the role of concurrency in accelerating the spread of HIV. Such a decrease could be the result of coital dilution - the reduction in per-partner coital frequency from additional partners - and/or increased condom use during concurrency. To study the effect of concurrency on the frequency of unprotected sex, we examined sexual behaviour data from three communities with high HIV prevalence around Cape Town, South Africa. Methods: We conducted a cross-sectional survey from June 2011 to February 2012 using audio computer-assisted self-interviewing to reconstruct one-year sexual histories, with a focus on coital frequency and condom use. Participants were randomly sampled from a previous TB and HIV prevalence survey. Mixed effects logistic and Poisson regression models were fitted to data from 527 sexually active adults reporting on 1210 relationship episodes to evaluate the effect of concurrency status on consistent condom use and coital frequency. Results: The median of the per-partner weekly average coital frequency was 2 (IQR: 1 - 3), and consistent condom use was reported for 36% of the relationship episodes. Neither per-partner coital frequency nor consistent condom use changed significantly during episodes of concurrency (aIRR = 1.05; 95% confidence interval (CI): 0.99-1.24 and aOR = 1.01; 95% CI: 0.38-2.68, respectively). Being male, coloured, having a tertiary education, and having a relationship between 2 weeks and 9 months were associated with higher coital frequencies. Being coloured, and having a relationship lasting for more than 9 months, was associated with inconsistent condom use. Conclusions: We found no evidence for coital dilution or for increased condom use during concurrent relationship episodes in three communities around Cape Town with high HIV prevalence. Given the low levels of self- reported consistent condom use, our findings suggest that if the frequency of unprotected sex with each of the sexual partners is sustained during concurrent relationships, HIV-positive individuals with concurrent partners may disproportionately contribute to onward HIV transmission

Progressive age-associated activation of JNK associates with conduction disruption in the aged atrium.

Connexin43 (Cx43) is critical for maintaining electrical conduction across atrial muscle. During progressive aging cardiac conduction slows and becomes susceptible to disruption, predisposing to arrhythmias. Changes in Cx43 protein expression, or its phosphorylation status, can instigate changes in the conduction of the cardiac action potential. Our study investigated whether increased levels of activated c-jun N-terminal kinase (JNK) is the mechanism responsible for the decline of Cx43 protein and intercellular communication during progressive aging. We examined right atrial muscle from guinea pigs between 1 day and 38 months of age. The area of the intercalated disc increased with age concurrent with a 75% decline in total C43 protein expression and spatial re-organisation of the remaining protein. An age-dependent increase in activated-JNK correlated with a rise in phosphorylated Cx43. The data also correlated with slowing of the action potential conduction velocity across the right atria from 0.38±0.01 m/s at 1 month of age to 0.30±0.01 m/s at 38 months of age. The JNK activator anisomycin increased levels of activated JNK in myocytes and reduced Cx43 protein expression paralleling the aging effect The JNK inhibitor SP600125, was found to eradicate almost all trace of Cx43 protein from the intercalating discs. We conclude that in vivo activation of JNK increases with age leading to the loss of Cx43 protein from atrial myocytes. This progressive loss results in impaired conduction and is likely to contribute to the increasing risk of atrial arrhythmias with advancing age

Exposure of Egyptian Rousette Bats (\u3ci\u3eRousettus aegyptiacus\u3c/i\u3e) and a Little Free-Tailed Bat (\u3ci\u3eChaerephon pumilus\u3c/i\u3e) to Alphaviruses in Uganda

The reservoir for zoonotic o’nyong-nyong virus (ONNV) has remained unknown since this virus was first recognized in Uganda in 1959. Building on existing evidence for mosquito bloodfeeding on various frugivorous bat species in Uganda, and seroprevalence for arboviruses among bats in Uganda, we sought to assess if serum samples collected from bats in Uganda demonstrated evidence of exposure to ONNV or the closely related zoonotic chikungunya virus (CHIKV). In total, 652 serum samples collected from six bat species were tested by plaque reduction neutralization test (PRNT) for neutralizing antibodies against ONNV and CHIKV. Forty out of 303 (13.2%) Egyptian rousettes from Maramagambo Forest and 1/13 (8%) little free-tailed bats from Banga Nakiwogo, Entebbe contained neutralizing antibodies against ONNV. In addition, 2/303 (0.7%) of these Egyptian rousettes contained neutralizing antibodies to CHIKV, and 8/303 (2.6%) contained neutralizing antibodies that were nonspecifically reactive to alphaviruses. These data support the interepidemic circulation of ONNV and CHIKV in Uganda, although Egyptian rousette bats are unlikely to serve as reservoirs for these viruses given the inconsistent occurrence of antibody-positive bats

TOI-3785 b: A Low-Density Neptune Orbiting an M2-Dwarf Star

Using both ground-based transit photometry and high-precision radial velocity (RV) spectroscopy, we confirm the planetary nature of TOI-3785 b. This transiting Neptune orbits an M2-Dwarf star with a period of ~4.67 days, a planetary radius of 5.14 +/- 0.16 Earth Radii, a mass of 14.95 +4.10, -3.92 Earth Masses, and a density of 0.61 +0.18, -0.17 g/cm^3. TOI-3785 b belongs to a rare population of Neptunes (4 Earth Radii < Rp < 7 Earth Radii) orbiting cooler, smaller M-dwarf host stars, of which only ~10 have been confirmed. By increasing the number of confirmed planets, TOI-3785 b offers an opportunity to compare similar planets across varying planetary and stellar parameter spaces. Moreover, with a high transmission spectroscopy metric (TSM) of ~150 combined with a relatively cool equilibrium temperature of 582 +/- 16 K and an inactive host star, TOI-3785 b is one of the more promising low-density M-dwarf Neptune targets for atmospheric follow-up. Future investigation into atmospheric mass loss rates of TOI-3785 b may yield new insights into the atmospheric evolution of these low-mass gas planets around M-dwarfs.Comment: 22 pages, 6 figures, 6 tables, Submitted to A

Dissecting the multifunctional role of the N-terminal disordered domain of a plant virus coat protein in RNA packaging, viral movement and interference with antiviral plant defense

[EN] The coat protein (CP) of Melon necrotic spot virus (MNSV) is structurally composed of three major domains. The middle S-domain builds a robust protein shell around the viral genome, whereas the C-terminal protruding domain, or P-domain, is involved in the attachment of virions to the transmission vector. Here, we have shown that the N-terminal domain, or R-domain, and the arm region, which connects the R-domain and S-domain, are involved in different key steps of the viral cycle, such as cell-to-cell movement and the suppression of RNA silencing and pathogenesis through their RNA-binding capabilities. Deletion mutants revealed that the CP RNA-binding ability was abolished only after complete, but not partial, deletion of the R-domain and the arm region. However, a comparison of the apparent dissociation constants for the CP RNA-binding reaction of several partial deletion mutants showed that the arm region played a more relevant role than the R-domain in in vitro RNA binding. Similar results were obtained in in vivo assays, although, in this case, full-length CPs were required to encapsidate full-length genomes. We also found that the R-domain carboxyl portion and the arm region were essential for efficient cell-to-cell movement, for enhancement of Potato virus X pathogenicity, for suppression of systemic RNA silencing and for binding of small RNAs. Therefore, unlike other carmovirus CPs, the R-domain and the arm region of MNSV CP have acquired, in addition to other essential functions such as genome binding and encapsidation functions, the ability to suppress RNA silencing by preventing systemic small RNA transport.This work was funded by grant BIO2014-54862-R from the Spanish Ministry of Science and Innovation and the Prometeo Program GV2014/010 from the Generalitat Valenciana. J.A.N. and M.S.-S. are the recipients of a postdoctoral contract and a PhD fellowship, respectively, from the Ministerio de Educacion y Ciencia of Spain. We thank L. Corachan for technical assistance. The authors have no conflicts of interest to declare.Serra Soriano, M.; Navarro Bohigues, JA.; Pallás Benet, V. (2017). Dissecting the multifunctional role of the N-terminal disordered domain of a plant virus coat protein in RNA packaging, viral movement and interference with antiviral plant defense. Molecular Plant Pathology. 18(6):837-849. https://doi.org/10.1111/mpp.12448S83784918

TOI-5205b: A Jupiter transiting an M dwarf near the Convective Boundary

We present the discovery of TOI-5205b, a transiting Jovian planet orbiting a solar metallicity M4V star, which was discovered using TESS photometry and then confirmed using a combination of precise radial velocities, ground-based photometry, spectra and speckle imaging. The host star TOI-5205 sits near the eponymous `Jao gap', which is the transition region between partially and fully-convective M dwarfs. TOI-5205b has one of the highest mass ratio for M dwarf planets with a mass ratio of almost 0.3$\%$, as it orbits a host star that is just $0.392 \pm 0.015$ $M_{\odot}$. Its planetary radius is $1.03 \pm 0.03~R_J$, while the mass is $1.08 \pm 0.06~M_J$. Additionally, the large size of the planet orbiting a small star results in a transit depth of $\sim 7\%$, making it one of the deepest transits of a confirmed exoplanet orbiting a main-sequence star. The large transit depth makes TOI-5205b a compelling target to probe its atmospheric properties, as a means of tracing the potential formation pathways. While there have been radial velocity-only discoveries of giant planets around mid M dwarfs, this is the first transiting Jupiter with a mass measurement discovered around such a low-mass host star. The high mass of TOI-5205b stretches conventional theories of planet formation and disk scaling relations that cannot easily recreate the conditions required to form such planets.Comment: Submitted to ApJ. Comments are welcome. arXiv admin note: text overlap with arXiv:2203.0717