Summary Previous experiments suggest a connection between the N-alpha-acetylation of proteins and the sensitivity of cells to apoptotic signals. Here, we describe a novel biochemical assay to detect the acetylation status of proteins and demonstrate that protein N-alpha-acetylation is regulated by the availability of acetyl-CoA. Because the anti-apoptotic protein Bcl-xL is known to influence mitochondrial metabolism, we reasoned that Bcl-xL may provide a link between protein N-alpha-acetylation and apoptosis. Indeed, Bcl-xL overexpression leads to a reduction in levels of acetyl-CoA and N-alpha-acetylated proteins in the cell. This effect is independent of Bax and Bak, the known binding partners of Bcl-xL. Increasing cellular levels of acetyl-CoA by addition of acetate or citrate restores protein N-alpha-acetylation in Bcl-xL-expressing cells and confers sensitivity to apoptotic stimuli. We conclude that acetyl-CoA serves as a signaling molecule that couples apoptotic sensitivity to metabolism by regulating protein N-alpha-acetylation.

A thiol group introduced on the gamma-carbon of lysine mediates robust native chemical ligation at both the alpha- and epsilon-amines in two consecutive steps. Desulfurization then affords the final product, in which the lysine residue at the ligation site has an isopeptide bond on its side chain. The method is useful for the synthesis of proteins containing special post-translational modifications on lysine.

Artemisinin is an effective anti-malarial drug isolated from Artemisia annua L. (Chinese wormwood), but the content of artemisinin in A. annua is low. In the present study we explored the possibility of using genetic engineering to increase the artemisinin content of A. annua by suppressing the expression of SQS (squalene synthase), a key enzyme of sterol pathway (a pathway competitive with that of artemisinin biosynthesis) by means of a hairpin-RNA-mediated RNAi (RNA interference) technique. A total of 23 independent transgenic A. annua plants were obtained through Agrobacterium tumefaciens-mediated transformation, which was confirmed by PCR and Southern-blot analyses. HPLC-evaporative light-scattering detection analysis showed that the artemisinin content of some transgenic plants was significantly increased, with the highest values reaching 31.4 mg/g dry weight, which is about 3.14-fold the content observed in untransformed control plants. Real-time reverse transcription-PCR analysis demonstrated that the expression of SQS was suppressed significantly, and GC-MS analysis showed that sterol was efficiently decreased in the transgenic plants. The present study demonstrated that genetic-engineering strategy of RNAi is an effective means of increasing artemisinin content in plants.

The Gravity Recovery and Climate Experiment (GRACE) mission ended its operation in October 2017, and the GRACE Follow-On mission was launched only in May 2018, leading to approximately 1 year of data gap. Given that GRACE-type observations are exclusively providing direct estimates of total water storage change (TWSC), it would be very important to bridge the gap between these two missions. Furthermore, for many climate-related applications, it is also desirable to reconstruct TWSC prior to the GRACE period. In this study, we aim at comparing different data-driven methods and identifying the more robust alternatives for predicting GRACE-like gridded TWSC during the gap and reconstructing them to 1992 using climate inputs. To this end, we first develop a methodological framework to compare different methods such as the multiple linear regression (MLR), artificial neural network (ANN), and autoregressive exogenous (ARX) approaches. Second, metrics are developed to measure the robustness of the predictions. Finally, gridded TWSC within 26 regions are predicted and reconstructed using the identified methods. Test computations suggest that the correlation of predicted TWSC maps with observed ones is more than 0.3 higher than TWSC simulated by hydrological models, at the grid scale of 1°r esolution. Furthermore, the reconstructed TWSC correctly reproduce the El Nino-Southern Oscillation (ENSO) signals. In general, while MLR does not perform best in the training process, it is more robust and could thus be a viable approach both for filling the GRACE gap and for reconstructing long-period TWSC fields globally when combined with statistical decomposition techniques.

Radicals at work: Radical‐mediated thiol‐ene addition of the thiol group of Cys to N‐vinylacetamide gives acetyl‐thialysine (KSAc), a near‐perfect mimic of acetyl‐lysine (see picture). The reaction is highly efficient with near quantitative conversion obtained in short reaction times. The generated KSAc is functionally identical or similar to its native counterpart.

With two β-mercaptoethyl groups on the N, a tertiary amide of structure 1 is always poised for intramolecular thioesterification however it flips about the C-N bond. It is shown that a peptide with such a C-terminal N,N-bis(2-mercaptoethyl)-amide (BMEA) can be used directly for native chemical ligation (NCL). These BMEA peptides are easily prepared with standard Fmoc-solid phase peptide synthesis protocols, thus giving a very convenient access to the thioester components for NCL.

The Total Water Storage Anomaly (TWSA) comprises all the water components on the Earth's continental areas and is the only variable that allows for comprehensively closing the terrestrial water budget, balancing precipitation, evapotranspiration, and runoff. Also, the TWSA is served as an important indicator of global climate change (Kusche et al., 2016).Since 2002, the Gravity Recovery and Climate Experiment (GRACE) satellites have measured the global total water storage anomalies with an unprecedented accuracy (Wahr et al., 2004). However, no effective measures could be used to monitor the global TWSA prior to the GRACE era (i.e., before 2002) and during the gap period (i.e., 2017-2018) of the GRACE and GRACE Follow-On (GRACE-FO) missions. Before the launch of GRACE, TWSA would have to be computed by aggregating storage changes simulated by hydrological models (Nie et al., 2019), possibly combined with in-situ gauge measurements of surface water levels or groundwater head (Seneviratne et al., 2004;Van Dijk et al., 2016;Chen et al., 2019). However, hydrological models rely on possibly biased forcing data, miss important process representations (e.g.,

The dual native chemical ligation at lysine strategy was revised by replacing the acid-labile Cbz protecting group with photolabile NVOC at the 4-mercaptolysine side chain. The optimized strategy was subsequently applied to the synthesis of K48-linked diubiquitin.