Photosystem II (PSII) water oxidation includes proton and electron transfer pathways, occurring during the sequential S-state transitions of MnCaO. Here, we investigate the charge separation events during the S to S tran...Photosystem II (PSII) water oxidation includes proton and electron transfer pathways, occurring during the sequential S-state transitions of MnCaO. Here, we investigate the charge separation events during the S to S transition that take place via the STyrZ intermediate, utilizing electron paramagnetic resonance (EPR) spectroscopy. The increasing number of cycles of STyrZ formation and decay results in a gradual diminution of the STyrZ signal intensity which is proportional to the amount of S state. Our results point to the progressive accumulation of a different configuration of the donor side of PSII at the S state that allows the MnCaO to be oxidized. These results consolidate previous investigations supporting that, during the lifetime of the STyrZ, a proton from MnCaO is removed, prior to the advancement to the S state.
It was previously shown that a fructose-rich diet (FRD) induces prediabetes, cardiac dysfunction, and hypertrophy (CH) in males. We assessed FRD and estrogen depletion on female metabolism and cardiovascular function. Fe...It was previously shown that a fructose-rich diet (FRD) induces prediabetes, cardiac dysfunction, and hypertrophy (CH) in males. We assessed FRD and estrogen depletion on female metabolism and cardiovascular function. Females on FRD or control diet (CD) did not develop prediabetes or cardiac dysfunction, although FRD-fed mice showed CH vs. CD. One month of ovariectomy (OVX) did not induce prediabetes, but FRD impaired glucose tolerance in OVX mice without additional metabolic or cardiac changes. Calcium transient amplitude decreased in OVX-FRD vs. SHAM-FRD, with delayed decay, suggesting reduced activity of the sarcoplasmic/endoplasmic reticulum Ca ATPase (SERCA2a). Sodium-hydrogen exchanger 1 (NHE1) expression also decreased in OVX-FRD. These findings indicate estrogen loss does not cause dysfunction but modifies glycemic response to FRD, while reduced NHE1 may help preserve cardiac function. Impact statement In ovariectomized (OVX) mice, estrogen deficiency leads to insulin resistance and impaired glucose tolerance only when combined with a fructose-rich diet (FRD); neither OVX nor FRD alone is sufficient to induce these alterations. However, despite hormonal changes, OVX mice fed a FRD do not develop significant cardiac dysfunction.
High glucose-induced endothelial dysfunction is a hallmark of diabetic microvascular complications. Reduced hydrogen sulphide (HS) levels and dysregulation of the HS-producing enzyme 3-mercaptopyruvate sulfurtransferase...High glucose-induced endothelial dysfunction is a hallmark of diabetic microvascular complications. Reduced hydrogen sulphide (HS) levels and dysregulation of the HS-producing enzyme 3-mercaptopyruvate sulfurtransferase (3-MST) are linked to this dysfunction. Dihydrolipoic acid (DHLA), formed from alpha-lipoic acid in mitochondria, has been proposed to enhance HS release from 3-MST; however, this has not been empirically tested in diabetes. Using a cell culture model, this study demonstrates that DHLA supplementation enhances HS production via 3-MST and improves endothelial function under high glucose conditions. Our results provide foundational knowledge and indicate that targeting the 3-MST/HS pathway via DHLA supplementation may have therapeutic potential to reduce or slow the onset and progression of diabetic microvascular complications.
The emergence of land plants from aquatic habitat over half a billion years ago marked a pivotal moment in Earth's history, profoundly altering both soil composition and atmospheric chemistry. This remarkable evolutionar...The emergence of land plants from aquatic habitat over half a billion years ago marked a pivotal moment in Earth's history, profoundly altering both soil composition and atmospheric chemistry. This remarkable evolutionary transition was accompanied by the establishment of multiple signaling pathways that facilitated plant adaptation to terrestrial environments. Among these, signaling pathways based on myo-inositol-derived cellular messengers have recently gained significant attention. Combinatorial attachment of phosphate to the myo-inositol (hereafter inositol) ring produces a large array of inositol phosphate (InsP) messengers that are involved in an ever-growing number of physiological processes in eukaryotes. Whether these messengers contributed to the emergence of land plants remains an open question. In this review, we explore recent advances in understanding the astonishing molecular diversity, biosynthesis and regulation of InsP molecules in plant cells, their integration into various physiological pathways, and the potential implications of InsP signaling pathways in the evolution of land plants.
The ability to align circadian phase to specific cues, or 'entrainment', is a defining feature of a circadian rhythm. Entrainment is critical for useful circadian function, as it enables organisms to determine the specif...The ability to align circadian phase to specific cues, or 'entrainment', is a defining feature of a circadian rhythm. Entrainment is critical for useful circadian function, as it enables organisms to determine the specific time of day to perform temporally restricted behavioural and physiological activities, ranging from sleep to cell division. While mammals have long been known to entrain their circadian rhythm, recent work has shed light on how this is achieved in every single cell, all of which maintain their own individual circadian oscillation. Here I will highlight the current understanding of how the major entraining cues of light, feeding and temperature are communicated to cells to alter their phase. Knowledge of the mechanisms of cellular entrainment has the capacity to impact both fundamental understanding of circadian rhythms and our application of cellular circadian research to real-world problems, including shift work.
Vibrio cholerae, the causative agent of cholera, uses surface proteins such as the repeats-in-toxin (RTX) adhesin FrhA to colonize hosts and initiate infection. Blocking bacterial adhesion represents a promising therapeu...Vibrio cholerae, the causative agent of cholera, uses surface proteins such as the repeats-in-toxin (RTX) adhesin FrhA to colonize hosts and initiate infection. Blocking bacterial adhesion represents a promising therapeutic strategy to treat infections without promoting drug resistance. FrhA contains a peptide-binding domain (PBD) that is key for hemagglutination, human epithelial cell binding, and V. cholerae biofilm formation. Previous studies identified a lead pentapeptide ligand with the sequence Ala-Gly-Tyr-Thr-Asp (AGYTD) that blocks V. cholerae colonization of the mouse small intestine at high micromolar concentrations. In this study, a structure-guided approach identified a minimal D-amino acid-containing tripeptide motif with higher affinity for the FrhA-PBD and predicted metabolic stability. Our results contribute to the development of anti-adhesion strategies to combat infections. Impact statement Our study elucidates the molecular basis of peptide recognition by the Vibrio cholerae adhesin FrhA and develops minimal D-amino-acid peptides that block adhesion with nanomolar affinity. These findings advance understanding of RTX adhesins and provide a structural blueprint for next-generation anti-adhesion therapeutics against cholera and related infections.
Circadian clocks allow for the physiological anticipation of daily environmental changes. A circadian rhythm in intracellular Mg was recently discovered in multiple eukaryotes. Given the pivotal role for Mg in metabolism...Circadian clocks allow for the physiological anticipation of daily environmental changes. A circadian rhythm in intracellular Mg was recently discovered in multiple eukaryotes. Given the pivotal role for Mg in metabolism, Mg rhythms could affect cellular energy expenditure over the daily cycle. To probe the potential mechanisms underlying the generation of cellular Mg rhythms, we present a phylogenetic analysis of Mg transport proteins. Extensive conservation was observed for ancestral prokaryotic proteins, identifying these as candidate proteins mediating Mg rhythms across eukaryotes. We also posit that shared allosteric regulation of Mg transport proteins might underlie Mg rhythms and propose a reciprocal feedback model between the rhythmic usage of Mg and rhythmic transport activity.
It has been proposed that the regulatory Sit4-associated protein subunit 3 (SAPS3) of protein phosphatase 6 (PP6C) acts as an AMP-activated protein kinase (AMPK) inhibitor by recruiting PP6C to dephosphorylate AMPKα-T172...It has been proposed that the regulatory Sit4-associated protein subunit 3 (SAPS3) of protein phosphatase 6 (PP6C) acts as an AMP-activated protein kinase (AMPK) inhibitor by recruiting PP6C to dephosphorylate AMPKα-T172. While we confirm this interaction in HEK293 cells, we find limited evidence for a SAPS3-AMPK interaction in metabolically perturbed liver and skeletal muscle from humans and mice. Across fasting, high-fat diet feeding and exercise conditions, co-immunoprecipitation assays failed to detect endogenous SAPS3-AMPK and PP6C-AMPK interactions. These findings challenge the physiological relevance of SAPS3/PP6C as regulators of AMPK in mature tissues and highlight the need for further investigation into the regulation of AMPK by protein phosphatases in vivo.
Mammalian cells express seven distinct phosphoinositide species: PI(3)P, PI(4)P, PI(5)P, PI(3,4)P, PI(3,5)P, PI(4,5)P, and PI(3,4,5)P. With the rapid development of labeling, imaging, and manipulation tools, our understa...Mammalian cells express seven distinct phosphoinositide species: PI(3)P, PI(4)P, PI(5)P, PI(3,4)P, PI(3,5)P, PI(4,5)P, and PI(3,4,5)P. With the rapid development of labeling, imaging, and manipulation tools, our understanding of the spatial distribution, functions, and regulation of these phosphoinositides has advanced significantly. Tightly regulated by lipid kinases, phosphatases, and lipid transfer proteins, each phosphoinositide exhibits a unique yet dynamic spatial distribution at both subcellular and suborganelle levels. This distinct spatial organization is critical for controlling membrane trafficking, defining organelle identity and function, mediating signal transduction, and supporting other essential cellular processes. Dysregulation of spatial phosphoinositide signaling has been linked to various human diseases. In this review, we provide a brief overview of current insights into the spatial organization of phosphoinositide signaling, highlighting its key roles in regulating membrane dynamics and signal transduction at the plasma membrane, endosomes and lysosomes, the Golgi apparatus, the ER, and the nucleus.
Vesicle fusion events are crucial for the survival of Giardia lamblia as they drive nutrient uptake and morphological stage transitions. Unlike most eukaryotes, Giardia has a minimal vesicular trafficking machinery. We r...Vesicle fusion events are crucial for the survival of Giardia lamblia as they drive nutrient uptake and morphological stage transitions. Unlike most eukaryotes, Giardia has a minimal vesicular trafficking machinery. We report a rare exception to this minimalism wherein two paralogues of N-ethylmaleimide-sensitive factor (NSF) are present in this parasite. Localization studies indicate that these highly homologous paralogues-GlNSF and GlNSF-likely function independently under various stress conditions, as GlNSF remains at peripheral vesicles, while the major pool of GlNSF redistributes to anterior flagella-associated structures. These paralogues also exhibit selective affinity for the α-soluble NSF attachment proteins (Glα-SNAPs). This selectivity stems from sequence divergences near their N termini. The two GlNSFs colocalize and coimmunoprecipitate, indicating the presence of a heterohexameric 20S complex in trophozoites. This study is the first to report the presence of a heterohexameric 20S complex and reveals adaptive specialization of vesicle trafficking machinery within a reduced eukaryotic system. Impact statement Here we report that a unicellular parasitic protist, Giardia lamblia, has two NSF paralogues, which is a rarity in eukaryotes. Although they share a high degree of homology, they are likely to discharge independent functions, especially under stress conditions.
Dipeptidyl peptidase IV (DPPIV) family proteases are classically defined by their strict removal of N-terminal dipeptides from substrates bearing a proline or alanine at the P position. Here, we report that both Caenorha...Dipeptidyl peptidase IV (DPPIV) family proteases are classically defined by their strict removal of N-terminal dipeptides from substrates bearing a proline or alanine at the P position. Here, we report that both Caenorhabditis elegans DPF-3 and human DPP4 (hDPP4) possess previously unrecognized tripeptidyl peptidase activity in addition to dipeptidyl peptidase activity. This activity plays a key role in the processing of the WAGO-1 protein N-terminus, which is essential for proper small-RNA loading, germline genome defense, and fertility. Kinetic analyses using the fluorogenic substrate H-Met-Gly-Pro-AMC further demonstrated that, in vitro, DPF-3 and hDPP4 can liberate AMC. These findings potentially expand the substrate repertoire of DPPIV proteases, suggesting that these proteases could function as versatile N-terminal processors, with important implications for nascent protein maturation.
The HtrA family of proteins is known for its dual role as chaperones and proteases. In Helicobacter pylori (H. pylori), HtrA's chaperone and proteolytic activities are crucial for the bacterium's survival and successful...The HtrA family of proteins is known for its dual role as chaperones and proteases. In Helicobacter pylori (H. pylori), HtrA's chaperone and proteolytic activities are crucial for the bacterium's survival and successful host infection. Compared to other HtrA homologs in Gram-negative bacteria, HtrA of H. pylori (HtrA) is rather well-understood. HtrA is localized in two cellular compartments, performing critical functions within the bacterial periplasm as well as in the extracellular milieu. This review aimed to summarize the current knowledge on HtrA and provide comprehensive information about (i) the structure, oligomerization, and general properties of HtrA, (ii) its chaperone and proteolytic activity in the stress response and the protein quality control system in the periplasm, and (iii) the functional role of HtrA in opening lateral cell junction complexes of epithelial cells as an important step in infectivity. Due to its essential physiological role and its contribution to the pathologic consequences of infection, HtrA represents a highly attractive target for novel therapeutic strategies.
Poly(ADP-ribose) polymerase-1 (PARP-1) is a multidomain enzyme essential for the DNA damage response; its inhibition can lead to cancer cell death. Recruitment of PARP-1 to sites of genomic damage is mediated by its zinc...Poly(ADP-ribose) polymerase-1 (PARP-1) is a multidomain enzyme essential for the DNA damage response; its inhibition can lead to cancer cell death. Recruitment of PARP-1 to sites of genomic damage is mediated by its zinc finger domains. In this study, we investigated the inhibition of PARP-1's DNA-dependent activation by three Au(I)-based drugs, presumable zinc-ejectors. We found that aurothioglucose and sodium aurothiomalate selectively inhibited PARP-1's DNA-dependent activity, with IC values in the nanomolar range, while preserving its DNA-independent activity. Furthermore, in a BRCA-mutated cell line, both compounds effectively suppressed DNA replication, with half-maximal effective concentrations (EC) also in the nanomolar range. These findings highlight the potential of selective, zinc finger-targeting PARP-1 inhibitors as promising candidates for anticancer drug testing. Impact statement The need to preserve basal poly(ADP-ribose) polymerase-1 (PARP-1) activity in healthy cells, along with the search for alternative anticancer therapies in cases of drug resistance, led to the discovery of selective and potent zinc finger-targeting inhibitors of PARP-1. This finding opens new opportunities for anticancer drug development.
Wound healing in the skin is a coordinated process in which the extracellular matrix (ECM) plays a central regulatory role. While the structural constituents of the ECM, such as collagens and elastin, are responsible for...Wound healing in the skin is a coordinated process in which the extracellular matrix (ECM) plays a central regulatory role. While the structural constituents of the ECM, such as collagens and elastin, are responsible for the shape and mechanical strength of the tissue, the modulatory functions of the ECM are largely mediated by nonstructural matricellular proteins. These proteins bind to structural ECM components, cell surface receptors and other extracellular molecules to fine-tune cellular behaviour throughout the different phases of wound healing. The signalling cascades evoked by matricellular proteins modulate key cellular processes, including proliferation, migration and differentiation-functions essential for effective tissue regeneration. This review provides an update about the mechanisms by which matricellular proteins orchestrate the wound healing process.
Y. Xu, J. He, Y. Wang, X. Zhu, Q. Pan, Q. Xie and F. Sun, "miR-889 Promotes Proliferation of Esophageal Squamous Cell Carcinomas Through DAB2IP," FEBS Letters 589, no. 10 (2015): 1127-1135, https://doi.org/10.1016/j.febs...Y. Xu, J. He, Y. Wang, X. Zhu, Q. Pan, Q. Xie and F. Sun, "miR-889 Promotes Proliferation of Esophageal Squamous Cell Carcinomas Through DAB2IP," FEBS Letters 589, no. 10 (2015): 1127-1135, https://doi.org/10.1016/j.febslet.2015.03.027. The above article, published online on 01 April 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors; the journal Editor-in-Chief, Michael Brunner; the Federation of European Biochemical Societies; and John Wiley & Sons Ltd. The retraction has been agreed upon following concerns raised by a third party. Following an investigation, duplicated elements were identified between Figures 2A and 5C, as well as between Figures 2B and 5C. Furthermore, inconsistencies were observed in the siDAB2IP colonies shown in Figures 4C and 4D. Finally, in Figure 6A, the 400x panel for Tumor #1 does not correspond to the 200x panel. The author cooperated with the investigation, stating that the duplications were an error due to figure mismanagement and provided some supporting data. However, the data provided was not considered to be satisfactory. Given the extent of the identified issues, the editors have lost confidence in the data presented and consider the conclusions to be compromised.
Expression of Concern: D.M. Price, C.L. Chik, D. Terriff, J. Weller, A. Humphries, D.A. Carter, D.C. Klein, and A.K. Ho, "Mitogen-Activated Protein Kinase Phosphatase-1 (MKP-1): >100-Fold Nocturnal and Norepinephrine-Ind...Expression of Concern: D.M. Price, C.L. Chik, D. Terriff, J. Weller, A. Humphries, D.A. Carter, D.C. Klein, and A.K. Ho, "Mitogen-Activated Protein Kinase Phosphatase-1 (MKP-1): >100-Fold Nocturnal and Norepinephrine-Induced Changes in the Rat Pineal Gland," FEBS Letters 577, no. 1-2 (2004): 220-226, https://doi.org/10.1016/j.febslet.2004.09.083. This Expression of Concern is for the above article, published online on 18 October 2004 in Wiley Online Library (wileyonlinelibrary.com), and has been issued by agreement between the journal Editor-in-Chief, Michael Brunner; Federation of European Biochemical Societies (FEBS); and John Wiley & Sons Ltd. A third party alerted the journal to possible duplications of the GADPH loading control bands in Figures 1B, 2B, and 3B. The journal verified the duplications and the publisher attempted to contact the authors for original data and comments. The authors did not respond to the publisher's requests. In the absence of the original data, the journal and publisher are unable to fully investigate the identified duplications. Therefore, the journal has decided to issue an Expression of Concern to inform and alert readers.
Phosphatidylinositol 4-kinases (PI4Ks) are pivotal enzymes responsible for the generation of phosphatidylinositol 4-phosphate (PI4P), a key precursor involved in various cellular signalling pathways that regulate vesicul...Phosphatidylinositol 4-kinases (PI4Ks) are pivotal enzymes responsible for the generation of phosphatidylinositol 4-phosphate (PI4P), a key precursor involved in various cellular signalling pathways that regulate vesicular trafficking, Golgi maintenance and intracellular communication. Conserved across eukaryotic species, PI4Ks exist in distinct isoforms with specific localisations and functions, ranging from plasma membrane dynamics to endosomal trafficking and autophagy regulation. Notably, numerous pathogens, including viruses, bacteria and parasites, have evolved mechanisms to hijack host PI4Ks, thereby facilitating intracellular replication and survival. For example, RNA viruses within the Flaviviridae and Coronaviridae families recruit PI4Ks to remodel host membranes for the assembly of replication complexes. Similarly, intracellular bacteria such as Salmonella and Legionella manipulate PI4P-enriched compartments to evade host defences and promote replication. Due to their central roles in both normal cellular physiology and infection, PI4Ks have emerged as promising therapeutic targets. A variety of inhibitors, including ATP-competitive compounds, have been developed and evaluated for their antiviral, antibacterial and antiparasitic potential. Nevertheless, challenges related to selectivity and toxicity remain. Recent advances include the identification of inhibitors effective against Plasmodium species and the development of compounds targeting PI4KIIIβ in infections with viruses such as hepatitis C and coronaviruses. This review highlights the dual role of PI4Ks as essential cellular regulators and exploitable pathogen cofactors, underscoring their potential as drug targets. Continued investigation into the structure, function and inhibition of PI4Ks may enable the development of selective therapeutic strategies for infectious diseases while minimising off-target effects on host cells.
The immune system exists in perpetual co-evolution with pathogens, and microbial pathogenesis is inexorably linked to the cyclical interactions between the pathogen and the host. Because pathogens exploit the immune syst...The immune system exists in perpetual co-evolution with pathogens, and microbial pathogenesis is inexorably linked to the cyclical interactions between the pathogen and the host. Because pathogens exploit the immune system in unique ways, the antimicrobial efficacy of any given immune process varies between pathogens, and the consequences of activation or inhibition of antimicrobial programs must be interpreted in the context of the given pathogen. An increasing body of literature shows that numerous facets of the immune system are tightly regulated by the circadian clock, with multiple immune processes demonstrating increased activity during certain times of the day. However, the field of circadian immunology has generally given its attention to unraveling the mechanism of circadian regulation and comparatively little attention to how these circadian oscillations may influence the ultimate outcome of diseases. Therefore, this review aims to interpret these findings in the context of a select number of clinically relevant pathogens: Salmonella enterica, Listeria monocytogenes, and Streptococcus pneumoniae. In this way, we hope to discuss the complex factors that determine how the circadian clock regulates disease progression.