WheyDerived Permeable Carbon Scaffolds pertaining to Cuboid Architectural

Published under license by The American Society for Biochemistry and Molecular Biology, Inc.Inter-α-inhibitor is a proteoglycan essential for mammalian reproduction and also plays a less well-characterized role in inflammation. It comprises two homologous "heavy chains" (HC1 and HC2) covalently attached to chondroitin sulfate on the bikunin core protein. Before ovulation HCs are transferred onto the polysaccharide hyaluronan (HA) to form covalent HC•HA complexes, thereby stabilizing an extracellular matrix around the oocyte required for fertilization. Additionally, such complexes form during inflammatory processes and mediate leukocyte adhesion in the synovial fluids of arthritis patients and protect against sepsis. Here using X-ray crystallography, we show that human HC1 has a structure similar to integrin β-chains, with a von Willebrand factor A domain, containing a functional metal ion-dependent adhesion site (MIDAS), and an associated hybrid domain. A comparison of the WT protein and a variant with an impaired MIDAS (but otherwise structurally identical) by small-angle X-ray scattering (SAXS) and analytical ultracentrifugation revealed that HC1 self-associates in a cation-dependent manner, providing a mechanism for HC•HA crosslinking and matrix stabilization. Surprisingly, unlike integrins, HC1 interacted with RGD-containing ligands, such as fibronectin, vitronectin and the latency-associated peptides of transforming growth factor β (TGFβ), in a MIDAS/cation-independent manner. However, HC1 utilizes its MIDAS motif to bind to and inhibit the cleavage of complement C3, and SAXS-based modeling indicates that this occurs through the inhibition of the alternative pathway C3 convertase. These findings provide detailed structural and functional insights into HC1 as a regulator of innate immunity, and further elucidate the role of HC•HA complexes in inflammation and ovulation. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.MutT homologue 1 (MTH1) removes oxidized nucleotides from the nucleotide pool and thereby prevents their incorporation into the genome and thereby reduces genotoxicity. We previously reported that MTH1 is an efficient catalyst of O6-methyl-dGTP hydrolysis suggesting that MTH1 may also sanitize the nucleotide pool from other methylated nucleotides. We here show that MTH1 efficiently catalyzes the hydrolysis of N6-methyl-dATP to N6-methyl-dAMP and further report that N6-methylation of dATP drastically increases the MTH1 activity. We also observed MTH1 activity with N6-methyl-ATP, albeit at a lower level. We show that N6-methyl-dATP is incorporated into DNA in vivo, as indicated by increased N6-methyl-dA DNA levels in embryos developed from MTH1 knock-out zebrafish eggs microinjected with N6-methyl-dATP compared with noninjected embryos. N6-methyl-dATP activity is present in MTH1 homologues from distantly related vertebrates, suggesting evolutionary conservation and indicating that this activity is important. Of note, N6-methyl-dATP activity is unique to MTH1 among related NUDIX hydrolases. Moreover, we present the structure of N6-methyl-dAMP-bound human MTH1, revealing that the N6-methyl group is accommodated within a hydrophobic active-site sub-pocket explaining why N6-methyl-dATP is a good MTH1 substrate. N6-methylation of DNA and RNA has been reported to have epigenetic roles and to affect mRNA metabolism. We propose that MTH1 acts in concert with adenosine deaminase-like protein isoform 1 (ADAL1) to prevent incorporation of N6-methyl-(d)ATP into DNA and RNA. This would hinder potential dysregulation of epigenetic control and RNA metabolism via conversion of N6-methyl-(d)ATP to N6-methyl-(d)AMP, followed by ADAL1 catalyzed deamination producing (d)IMP that can enter the nucleotide salvage pathway. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.β-Glucocerebrosidase (GBA) hydrolyzes glucosylceramide (GlcCer) to generate ceramide. Previously, we demonstrated that lysosomal GBA1 and non-lysosomal GBA2 possess not only GlcCer hydrolase activity, but also transglucosylation activity to transfer the glucose residue from GlcCer to cholesterol to form β-cholesterylglucoside (β-GlcChol) in vitro β-GlcChol is a member of sterylglycosides present in diverse species. How GBA1 and GBA2 mediate β-GlcChol metabolism in the brain is unknown. Here, we purified and characterized sterylglycosides from rodent and fish brains. Although glucose is thought to be the sole carbohydrate component of sterylglycosides in vertebrates, structural analysis of rat brain sterylglycosides revealed the presence of galactosylated cholesterol (β-GalChol), in addition to β-GlcChol. Analyses of brain tissues from GBA2-deficient mice and GBA1- and/or GBA2-deficient Japanese rice fish (Oryzias latipes) revealed that GBA1 and GBA2 are responsible for β-GlcChol degradation and formation, respectively, and that both GBA1 and GBA2 are responsible for β-GalChol formation. Liquid chromatography-tandem mass spectrometry revealed that β-GlcChol and β-GalChol are present throughout development from embryo to adult in mouse brain. We found that β-GalChol expression depends on galactosylceramide (GalCer) and developmental onset of β-GalChol biosynthesis appeared to be during myelination. We also found that β-GlcChol and β-GalChol are secreted from neurons and glial cells in association with exosomes. In vitro enzyme assays confirmed that GBA1 and GBA2 have transgalactosylation activity to transfer the galactose residue from GalCer to cholesterol to form β-GalChol. This is the first report of the existence of β-GalChol in vertebrates and how β-GlcChol and β-GalChol are formed in the brain. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.Sulfur is essential for biological processes such as amino acid biogenesis, iron-sulfur cluster formation, and redox homeostasis. To acquire sulfur-containing compounds from the environment, bacteria have evolved high-affinity uptake systems, predominant among which is the ABC transporter family. Selleck GSK269962A Theses membrane-embedded enzymes use the energy of ATP hydrolysis for transmembrane transport of a wide range of biomolecules against concentration gradients. Three distinct bacterial ABC import systems of sulfur-containing compounds have been identified, but the molecular details of  their transport mechanism remain poorly characterized. Here, we provide results from a biochemical analysis of the purified Escherichia coli YecSC-FliY cysteine/cystine import system. We found that the substrate-binding protein (SBP) FliY binds L-cystine, L-cysteine, and D-cysteine with micromolar affinities. However, binding of the L- and D-enantiomers induced different conformational changes of FliY, where the L- enantiomer/SBP complex interacted more efficiently with the YecSC transporter. YecSC had low basal ATPase activity that was moderately stimulated by apo-FliY, more strongly by D-cysteine-bound FliY, and maximally by L-cysteine- or L-cystine-bound FliY. However, at high FliY concentrations, YecSC reached maximal ATPase rates independently of the presence or nature of the substrate. These results suggest that FliY exists in a conformational equilibrium between an open, unliganded form that does not bind to the YecSC transporter, and closed, unliganded and closed, liganded forms that bind this transporter with variable affinities yet equally stimulate its ATPase activity. These findings differ from previous observations for similar ABC transporters, highlighting the extent of mechanistic diversity in this large protein family. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.Accumulating evidence suggests that brown adipose tissue (BAT) is a potential therapeutic target for managing obesity and related diseases. PGAM family member 5, mitochondrial serine/threonine protein phosphatase (PGAM5) is a protein phosphatase that resides in the mitochondria and regulates many biological processes, including cell death, mitophagy, and immune responses. Since BAT is a mitochondria-rich tissue, we have hypothesized that PGAM5 has a physiological function in BAT. We previously reported that PGAM5-knockout (KO) mice are resistant to severe metabolic stress. Importantly, lipid accumulation is suppressed in PGAM5-KO BAT, even under unstressed conditions, raising the possibility that PGAM5 deficiency stimulates lipid consumption. However, the mechanism underlying this observation is undetermined. Here, using an array of biochemical approaches, including quantitative RT-PCR, immunoblotting, and oxygen consumption assays, we show that PGAM5 negatively regulates energy expenditure in brown adipocytes. We found that PGAM5-KO brown adipocytes have an enhanced oxygen consumption rate and increased expression of uncoupling protein 1 (UCP1), a protein that increases energy consumption in the mitochondria. Mechanistically, we found that PGAM5 phosphatase activity and intramembrane cleavage are required for suppression of UCP1 activity. Furthermore, utilizing a genome-wide siRNA screen in HeLa cells to search for regulators of PGAM5 cleavage, we identified a set of candidate genes, including phosphatidylserine decarboxylase (PISD), which catalyzes the formation of phosphatidylethanolamine at the mitochondrial membrane. Taken together, these results indicate that PGAM5 suppresses mitochondrial energy expenditure by down-regulating UCP1 expression in brown adipocytes and that its phosphatase activity and intramembrane cleavage are required for UCP1 suppression. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.A hallmark of the mammalian immune system is its ability to respond efficiently to foreign antigens without eliciting an inappropriate response to self-antigens. Furthermore, a robust immune response requires the coordination of a diverse range of cells present at low frequencies within the host. This problem is solved, in part, by concentrating antigens, antigen-presenting cells and antigen-responsive cells in lymph nodes (LNs). Beyond housing these cell types in one location, LNs are highly organized structures consisting of pre-positioned cells within well-defined microanatomical niches. In this Cell Science at a Glance article and accompanying poster, we outline the key cellular populations and components of the LN microenvironment that are present at steady state and chronicle the dynamic changes in these elements following an immune response. This review highlights the LN as a staging ground for both innate and adaptive immune responses, while providing an elegant example of how structure informs function. © 2020. Published by The Company of Biologists Ltd.The bone marrow is a spatially restricted niche, housing cells of the hematopoietic and mesenchymal lineages in various hierarchical commitment states. Although highly localized, cells within this niche are also subject to regulation by environmental and/or circulatory changes through extensive vascularization. Bone marrow adipocytes, derived from mesenchymal stem cells and once known as marrow space fillers, are a heterogeneous population. These cells reside in distinct niches within the bone marrow and interact with proximal cells, such as hematopoietic precursors and lineage-committed cells. In this diverse cellular milieu, bone marrow adipocytes influence commitment decisions and cellular lineage selection by interacting with stem and progenitor cells. In addition, bone marrow adipocytes respond to environmental changes, such as obesity, by undergoing hypertrophy, hyperplasia or adoption of characteristics resembling those of peripheral brown, beige or white adipocytes. Here, we review recent findings and concepts on the influence of bone marrow adipocytes on hematopoietic and other cellular lineages within this niche.