Numerous iron-sulfur (Fe-S) proteins with diverse functions are present in the matrix and respiratory chain complexes of mitochondria. Although [4Fe-4S] clusters are the most common type of Fe-S cluster in mitochondria, the molecular mechanism of [4Fe-4S] cluster assembly and insertion into target proteins by the mitochondrial iron-sulfur cluster (ISC) maturation system is not well-understood. Here we report a detailed characterization of two late-acting Fe-S cluster-carrier proteins from Arabidopsis thaliana, NFU4 and NFU5. Yeast two-hybrid and bimolecular fluorescence complementation studies demonstrated interaction of both the NFU4 and NFU5 proteins with the ISCA class of Fe-S carrier proteins. Recombinant NFU4 and NFU5 were purified as apo-proteins after expression in Escherichia coli. In vitro Fe-S cluster reconstitution led to the insertion of one [4Fe-4S]2+ cluster per homodimer as determined by UV-visible absorption/CD, resonance Raman and EPR spectroscopy, and analytical studies. Cluster transfer reactions, monitored by UV-visible absorption and CD spectroscopy, showed that a [4Fe-4S]2+ cluster-bound ISCA1a/2 heterodimer is effective in transferring [4Fe-4S]2+ clusters to both NFU4 and NFU5 with negligible back reaction. In addition, [4Fe-4S]2+ cluster-bound ISCA1a/2, NFU4, and NFU5 were all found to be effective [4Fe-4S]2+ cluster donors for maturation of the mitochondrial apo-aconitase 2 as assessed by enzyme activity measurements. The results demonstrate rapid, unidirectional, and quantitative [4Fe-4S]2+ cluster transfer from ISCA1a/2 to NFU4 or NFU5 that further delineates their respective positions in the plant ISC machinery and their contributions to the maturation of client [4Fe-4S] cluster-containing proteins.

R. Greg Stacey
Nov 4, 2020; 0:RA120.002275v1-mcp.RA120.002275
Research

Using a simple, environment friendly proteome extraction (TOP), we were able to optimize the analysis of clinical samples. Using our TOP method we analyzed a clinical cohort of microsatellite stable (MSS) and unstable (MSI-H) colorectal carcinoma (CRC). We identified a tumor cell specific, STAT1-centered, immune signature expressed by the MSI-H tumor cells. We then showed that long, but not short, exposure to Interferon- induces a similar signature in vitro. We identified 10 different temporal protein expression patterns, classifying the Interferon- protein temporal regulation in CRC. Our data sheds light on the changes that tumor cells undergo under long-term immunological pressure in vivo, the importance of STAT proteins in specific biological scenarios. The data generated could help find novel clinical biomarkers and therapeutic approaches.

Biological functions emerge from complex and dynamic networks of protein-protein interactions. Because these protein-protein interaction networks, or interactomes, represent pairwise connections within a hierarchically organized system, it is often useful to identify higher-order associations embedded within them, such as multi-member protein complexes. Graph-based clustering techniques are widely used to accomplish this goal, and dozens of field-specific and general clustering algorithms exist. However, interactomes can be prone to errors, especially when inferred from high-throughput biochemical assays. Therefore, robustness to network-level noise is an important criterion for any clustering algorithm that aims to generate robust, reproducible clusters. Here, we tested the robustness of a range of graph-based clustering algorithms in the presence of noise, including algorithms common across domains and those specific to protein networks. Strikingly, we found that all of the clustering algorithms tested here markedly amplified noise within the underlying protein interaction network. Randomly rewiring only 1% of network edges yielded more than a 50% change in clustering results, indicating that clustering markedly amplified network-level noise. Moreover, we found the impact of network noise on individual clusters was not uniform: some clusters were consistently robust to injected noise while others were not. To assist in assessing this, we developed the clust.perturb R package and Shiny web application to measure the reproducibility of clusters by randomly perturbing the network. We show that clust.perturb results are predictive of real-world cluster stability: poorly reproducible clusters as identified by clust.perturb are significantly less likely to be reclustered across experiments. We conclude that graph-based clustering amplifies noise in protein interaction networks, but quantifying the robustness of a cluster to network noise can separate stable protein complexes from spurious associations.

Billy Napier will remain in place as head football coach at Florida, despite the Gators producing another lackluster campaign during his third season, athletic director Scott Stricklin announced Thursday.

Aug. 19, 2024 — SURF’s innovation department recently collaborated with Cornelis Networks to advance networking capabilities for high-performance computing (HPC) clusters. The collaboration marks a new step forward for SURF […]

The post Cornelis Networks Partners with SURF to Enhance HPC Cluster Networking Capabilities appeared first on HPCwire.

The precise regulation of Ca²⁺ signals plays a crucial role in the physiological functions of neurons. Here, we investigated the rapid effect of glucocorticoids on Ca²⁺ signals in cultured hippocampal neurons from both female and male rats. In cultured hippocampal neurons, glucocorticoids inhibited the spontaneous somatic Ca²⁺ spikes generated by Kv2.1-organized Ca²⁺ microdomains. Furthermore, glucocorticoids rapidly reduced the cell surface expressions of Kv2.1 and Ca_V1.2 channels in hippocampal neurons. In HEK293 cells transfected with Kv2.1 alone, glucocorticoids significantly reduced the surface expression of Kv2.1 with little effect on K⁺ currents. In HEK293 cells transfected with Ca_V1.2 alone, glucocorticoids inhibited Ca_V1.2 currents but had no effect on the cell surface expression of Ca_V1.2. Notably, in the presence of wild-type Kv2.1, glucocorticoids caused a decrease in the surface expression of Ca_V1.2 channels in HEK293 cells. However, this effect was not observed in the presence of nonclustering Kv2.1S586A mutant channels. Live-cell imaging showed that glucocorticoids rapidly decreased Kv2.1 clusters on the plasma membrane. Correspondingly, Western blot results indicated a significant increase in the cytoplasmic level of Kv2.1, suggesting the endocytosis of Kv2.1 clusters. Glucocorticoids rapidly decreased the intracellular cAMP concentration and the phosphorylation level of PKA in hippocampal neurons. The PKA inhibitor H89 mimicked the effect of glucocorticoids on Kv2.1, while the PKA agonist forskolin abrogated the effect. In conclusion, glucocorticoids rapidly suppress Ca_V1.2-mediated Ca²⁺ signals in hippocampal neurons by promoting the endocytosis of Kv2.1 channel clusters through reducing PKA activity.

Title: Nasal Spray May Ease Cluster Headaches
Category: Health News
Created: 8/29/2007 12:00:00 AM
Last Editorial Review: 8/29/2007 12:00:00 AM

PURPOSE

We undertook a trial to test the efficacy of a technology-assisted health coaching intervention for weight management, called Goals for Eating and Moving (GEM), within primary care.

This stunning new image from the NASA/ESA Hubble Space Telescope is one of the best ever views of a galaxy duo called MCG+05-31-045.

The post Hubble Spots Pair of Interacting Galaxies in Coma Cluster appeared first on Sci.News: Breaking Science News.

Incredible illustrations by Paris based artist - Yukiko Noritake. She works with Louis Vuitton, Piaget, Airbnb, Elle and other...

Amazing illustrations by Masha Foya...

HealthMap Surveillance Efforts Illustrate Global Epidemiology of H1N1 Spread

प्लेटफॉर्म- नेटफ्लिक्स 'लस्ट स्टोरीज 2' एक एंथोलॉजी यानि की संकलन है, जहां 4 कहानियां हमें 'लस्ट' यानि की वासना के अलग अलग रूप को दिखाती है। ये कहानियां अलग-अलग किरदारों को दिखाती है, जिसके अलग-अलग अनुभव और अलग

Sparrow, Giles, 1970- author

Cooper, Nancy, 1967- author

Levy, Debbie, author

Oxlade, Chris, author

Singh, Rina, 1955- author

Charlton-Trujillo, e. E., author

Hart, Caryl, author

Van Draanen, Wendelin, author

Rosenstock, Barb, author

Sullivan, Kathy, 1951- author

Lightman, Alan P., 1948- author

Lang, Heather, 1966- author

Fehr, Daniel, author, translator

Rylant, Cynthia, author

Sonenshine, Randi, 1968- author

Vickers, Elaine, author

Schaefer, Lola M., 1950- author

Haft, Sheryl, author