Evolutionary insights into the microneme-secreted, chitinase-containing high molecular weight protein complexes involved in Plasmodium invasion of the mosquito midgut

While general mechanisms by which Plasmodium ookinetes invade the mosquito midgut have been studied, details remain to be understood regarding the interface of the ookinete, specifically its barriers to invasion, such as the proteolytic milieu, the chitin-containing, protein cross-linked peritrophic matrix, and the midgut epithelium. Here we review knowledge of Plasmodium chitinases and the mechanisms by which they mediate the ookinete crossing the peritrophic matrix. The integration of new genomic insights into previous findings advances our understanding of Plasmodium evolution. Recently obtained Plasmodium spp. genomic data enable identification of the conserved residues in the experimentally demonstrated hetero-multimeric, high molecular weight complex comprised of a short chitinase covalently linked to binding partners, von Willebrand factor A domain-related protein (WARP) and secreted ookinete adhesive protein (SOAP). Artificial intelligence-based high-resolution structural modeling using the DeepMind AlphaFold algorithm yielded highly informative 3D structures and insights into how short chitinases, WARP, and SOAP may interact at the atomic level to form the ookinete-secreted peritrophic matrix invasion complex. Elucidating the significance of the divergence of ookinete-secreted micronemal proteins among Plasmodium species could lead to a better understanding of ookinete invasion machinery and the co-evolution of Plasmodium -mosquito interactions.

Deciphering PD1 activation mechanism from molecular docking and molecular dynamic simulations

The activation of T cells is normally accompanied by inhibitory mechanisms within which the PD1 receptor stands out. Upon binding the ligands PDL1 and PDL2, PD1 drives T cells to an unresponsive state called exhaustion characterized by a markedly decreased capacity to exert effector functions. For this reason, PD1 has become one of the most important targets in cancer immunotherapy. Despite the numerous studies about PD1 signaling modulation, how the PD1 signaling is activated upon the ligands’ binding remains an open question. Several experimental facts suggest that the activation of the PD1-PLD1 pathway depends on the interaction with an unknown partner at the cellular membrane. In this work, we investigate the possibility that the target of PD1-PDL1 is the same PD1-PDL1 complex. We combined molecular docking to explore different binding modes with molecular dynamics and umbrella sampling simulations to assess the complexes’ stability. We found a high molecular weight complex that explains the activation of PD1 upon PDL1 binding. This complex has an affinity comparable to the PD1-PDL1 interaction and resembles the form of a linear lattice.

Identification of macrotroponin T: findings from a case report and non-reproducible troponin T results

Objectives Macrotroponin is due to cardiac troponin (cTn) binding to endogenous cTn autoantibodies. While previous studies showed a high incidence of macrotroponin affecting cTnI assays, reports of macrotroponin T, particularly without cTnI reactivity, have been rare. Although the clinical significance of macrotroponin is not fully understood, macroenzymes and complexes are recognised to cause confusion in interpretation of laboratory results. The potential for adverse clinical consequences due to misinterpretation of affected results is very high. Methods We describe four cases of macrotroponin T with persistently low high sensitivity cTnT (hs-cTnT) by the 9 min compared to the 18 min variant of the assay. Three cases were serendipitously identified due to the use of a lot number of Roche hs-cTnT affected by non-reproducible results, necessitating measurement of cTnT in duplicate. We identified and characterised these macrotroponin specimens by immunoglobulin depletion (Protein A and PEG precipitation), mixing studies with EDTA and recombinant cTnT. Results In cases of macro-cTnT, a lower result occurred on the hs-cTnT using the 9 min compared to 18 min variant assay (ratio of 9–18 min hs-cTnT <0.80). Mixing studies with recombinant cTnT or EDTA demonstrated a difference in recovery vs. controls. One of these patients demonstrated a high molecular weight complex for cTnI and cTnT demonstrating a macrocomplex involving both cTn. This patient demonstrated a rise and fall in cTn when measured by several commercial assays consistent with genuine acute cardiac injury. Conclusions We identified several cases of macro-cTnT and described associated clinical and biochemical features.

Reduced protein kinase C delta association with a higher molecular weight complex in mitochondria of Barth Syndrome lymphoblasts

Protein kinase C delta (PKCδ) is a signaling kinase that regulates several cellular responses and is controlled via multi-site phosphorylation. The PKCδ signalosome exists as a high molecular weight complex in mitochondria and adjusts the fuel flux from glycolytic sources to the intensity of mitochondrial respiration, thus controlling mitochondrial oxidative phosphorylation. In the X-linked genetic disease Barth Syndrome (BTHS) mitochondrial oxidative phosphorylation is impaired due to a mutation in the TAFAZZIN gene which results in reduction in the phospholipid cardiolipin (CL) and an accumulation of monolysocardiolipin (MLCL). We previously demonstrated, through phosphokinome analysis, that phosphorylation of PKCδ is altered on multiple sites in BTHS patient lymphoblasts. In this study, we examined if PKCδ association with a higher molecular weight complex was altered in mitochondria of BTHS lymphoblasts. BTHS lymphoblasts exhibited reduction in all molecular species of CL examined and accumulation of trioleoyl-MLCL. Immunoblot analysis of blue native-polyacrylamide gel electrophoresis mitochondrial fractions revealed that PKCδ was associated with a higher molecular weight complex and that this was markedly reduced in BTHS patient B lymphoblasts compared to controls in spite of an increase in PKCδ protein expression. The elevated expression level of PKCδ in BTHS lymphoblasts was associated with increased citrate synthase activity indicative of abnormal mitochondrial proliferation. We hypothesize that the lack of PKCδ within this higher molecular weight complex may contribute to defective mitochondrial PKCδ signaling and thus to the bioenergetic defects observed in BTHS.

The RabGAP TBC-11 controls Argonaute localization for proper microRNA function in C. elegans

Once loaded onto Argonaute proteins, microRNAs form a silencing complex called miRISC that targets mostly the 3’UTR of mRNAs to silence their translation. How microRNAs are transported to and from their target mRNA remains poorly characterized. While some reports linked intracellular trafficking to microRNA activity, it is still unclear how these pathways coordinate for proper microRNA-mediated gene silencing and turnover. Through a forward genetic screen using Caenorhabditis elegans, we identified the RabGAP tbc-11 as an important factor for the microRNA pathway. We show that TBC-11 acts mainly through the small GTPase RAB-6 and that its regulation is required for microRNA function. The absence of functional TBC-11 increases the pool of microRNA-unloaded Argonaute ALG-1 that is likely associated to endomembranes. Furthermore, in this condition, this pool of Argonaute accumulates in a perinuclear region and forms a high molecular weight complex. Altogether, our data suggest that the alteration of TBC-11 generates a fraction of ALG-1 that cannot bind to target mRNAs, leading to defective gene repression. Our results establish the importance of intracellular trafficking for microRNA function and demonstrate the involvement of a small GTPase and its GAP in proper Argonaute localization in vivo.

Scientific substantiation of the concentration of excipients for the manufacture of eye drops Angiolin

Throughout human history, cataracts have been one of the leading causes of blindness. For this disease, we studied the market of drugs of domestic and foreign production. The object of our study was the subgroup S10X Other ophthalmic drugs. Employees of the Department of Pharmaceutical Chemistry of Zaporizhzhia State Medical University (ZSMU) together with specialists of the NGO “Pharmatron” was synthesized a new compound, which was named Angiolin. A rational dosage form in the form of eye drops was proposed for the new drug. Since the drops continue to be the most common and widely used in practice dosage form. We have previously selected the optimal content of the active substance in eye drops. As is known from the technological parameters, eye drops must be isotonic, ie in their composition should be added excipients. The aim of our work is to select the concentration of excipients for the manufacture of eye drops Angiolin. Materials and methods. During the work at the Department of Pharmaceutical Chemistry of ZSMU, three solutions of eye drops Angiolin with different composition were prepared, and later the theoretical osmolarity was calculated. Results. Accurate theoretical calculation of the osmolarity of solutions containing substances with high molecular weight, complex total extracts, and highly concentrated solutions is impossible. Since the excipient was used methylcellulose, it was better to perform such a calculation experimentally, through the determination of osmolality. On the basis of the conducted researches, for correction of osmolarity, we were chosen – sodium chloride. Sodium chloride was selected at a concentration of 7.0 g/l, which creates an osmolality of the drug equal to 234.3 mosmol/kg. The estimated value at the same concentration of sodium chloride was 239.56 mosmol/l. The value of osmolarity of eye drops was calculated from it makes 302,18 mosmol/l that was confirmed the correctness of the chosen concentration of sodium chloride as a part of eye drops. Conclusions. Based on the above, we selected the concentration of excipients for the manufacture of eye drops Angiolin.

Plastic Pollution and Climate Change: Role of Bioremediation as a Tool to Achieving Sustainability

Pollution from post-consumer plastics is a growing global environmental challenge whose negative impacts are exacerbating climate change. Plastics are stable, durable, and hydrophobic. They possess high molecular weight, complex three-dimensional structure, and are not readily available to be used as substrate by biological agents such as microorganisms and enzymes. Polyethylene terephthalate (PET) is one of the examples of petrochemical-based plastics. PET is a strong, clear, and light-weight plastic with global usage in the production of bottles. Technological innovation, policy formulation, advocacy and sensitization, change in consumption pattern, and bioremediation are some of the approaches that are currently being used to mitigate environmental pollution from post-consumer PET bottles. The ubiquitous property of microorganisms and their ability to survive in almost every environment, including very extreme ones, make them good candidate for biodegradation. Bioremediation is simply defined as engineered or enhanced biodegradation. This review discusses the potential of bioremediation as sustainable and environment-friendly tool to clean up post-consumer PET bottles that already accumulate on land, in soil, and in water bodies.

The molecular chaperone β-casein prevents amorphous and fibrillar aggregation of α-lactalbumin by stabilisation of dynamic disorder

Deficits in protein homeostasis (proteostasis) are typified by the partial unfolding or misfolding of native proteins leading to amorphous or fibrillar aggregation, events that have been closely associated with diseases including Alzheimer's and Parkinson's diseases. Molecular chaperones are intimately involved in maintaining proteostasis, and their mechanisms of action are in part dependent on the morphology of aggregation-prone proteins. This study utilised native ion mobility–mass spectrometry to provide molecular insights into the conformational properties and dynamics of a model protein, α-lactalbumin (α-LA), which aggregates in an amorphous or amyloid fibrillar manner controlled by appropriate selection of experimental conditions. The molecular chaperone β-casein (β-CN) is effective at inhibiting amorphous and fibrillar aggregation of α-LA at sub-stoichiometric ratios, with greater efficiency against fibril formation. Analytical size-exclusion chromatography demonstrates the interaction between β-CN and amorphously aggregating α-LA is stable, forming a soluble high molecular weight complex, whilst with fibril-forming α-LA the interaction is transient. Moreover, ion mobility–mass spectrometry (IM-MS) coupled with collision-induced unfolding (CIU) revealed that α-LA monomers undergo distinct conformational transitions during the initial stages of amorphous (order to disorder) and fibrillar (disorder to order) aggregation. The structural heterogeneity of monomeric α-LA during fibrillation is reduced in the presence of β-CN along with an enhancement in stability, which provides a potential means for preventing fibril formation. Together, this study demonstrates how IM-MS and CIU can investigate the unfolding of proteins as well as examine transient and dynamic protein–chaperone interactions, and thereby provides detailed insight into the mechanism of chaperone action and proteostasis mechanisms.

Integrated proteogenetic analysis reveals the landscape of a mitochondrial-autophagosome synapse during PARK2-dependent mitophagy

The PINK1 protein kinase activates the PARK2 ubiquitin ligase to promote mitochondrial ubiquitylation and recruitment of ubiquitin-binding mitophagy receptors typified by OPTN and TAX1BP1. Here, we combine proximity biotinylation of OPTN and TAX1BP1 with CRISPR-Cas9–based screens for mitophagic flux to develop a spatial proteogenetic map of PARK2-dependent mitophagy. Proximity labeling of OPTN allowed visualization of a “mitochondrial-autophagosome synapse” upon mitochondrial depolarization. Proximity proteomics of OPTN and TAX1BP1 revealed numerous proteins at the synapse, including both PARK2 substrates and autophagy components. Parallel mitophagic flux screens identified proteins with roles in autophagy, vesicle formation and fusion, as well as PARK2 targets, many of which were also identified via proximity proteomics. One protein identified in both approaches, HK2, promotes assembly of a high–molecular weight complex of PINK1 and phosphorylation of ubiquitin in response to mitochondrial damage. This work provides a resource for understanding the spatial and molecular landscape of PARK2-dependent mitophagy.

Re-Evaluating the Mechanism of Action of α,β-Unsaturated Carbonyl DUB Inhibitors B-AP15 and VLX1570: A Paradigmatic Example of Unspecific Protein Crosslinking with Michael Acceptor Motif-Containing Drugs

<div>Deubiquitinating enzymes are a growing target class across multiple disease states, with several inhibitors now reported. b-AP15 and VLX1570 are two structurally related USP14/UCH-37 inhibitors with a shared α,β-unsaturated carbonyl substructure motif. Initially taken forward into a phase I/II clinical trial for refractory multiple myeloma, VLX1570 has since been put on full clinical hold due to dose limiting toxicity. Through a proteomic approach, here we demonstrate that these compounds target a diverse range of proteins, resulting in the formation of higher molecular weight complexes. Activity-based proteome profiling identified CIAPIN1 as a sub-micromolar covalent target of VLX1570, and further analysis demonstrated that high molecular weight complex formation leads to aggregation of CIAPIN1 in intact cells. Our results suggest that in addition to DUB inhibition, these compounds induce non-specific protein aggregation through cross-linking, providing a molecular explanation for general cellular toxicity.</div>