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The CXXC domain is a reader of DNA methylation which preferentially binds to unmethylated CpG DNA motifs. Chromosomal translocations involving the

Deubiquitinase A (DUBA) belongs to the ovarian tumor family of deubiquitinating enzymes and was initially identified as a negative regulator of type I interferons, whose overproduction has been linked to autoimmune diseases. The deubiquitinating activity of DUBA is positively regulated by phosphorylation at a single serine residue, S177, which results in minimal structural changes. We have previously shown that phosphorylation induces a two-state conformational equilibrium observed only in the active form of DUBA, highlighting the functional importance of DUBA dynamics. Here, we report the conformational dynamics of DUBA on the microsecond-to-millisecond time scales characterized by nuclear magnetic resonance relaxation dispersion experiments. We found that motions on these time scales are highly synchronized in the phosphorylated and nonphosphorylated DUBA. Despite the overall similarity of these two forms, different dynamic properties were observed in helix α1 and the neighboring regions, including residue S177, which likely contribute to the activation of DUBA by phosphorylation. Moreover, our data suggest that transient unfolding of helix α6 drives the global conformational process and that mutations can be introduced to modulate this process, which provides a basis for future studies to define the exact functional roles of motions in DUBA activation and substrate specificity.

AF9 (MLLT3) and ENL (MLLT1) are members of the YEATS family (named after the five proteins first shown to contain this domain: Yaf9, ENL, AF9, Taf14, Sas5) defined by the presence of a YEATS domain. The YEATS domain is an epigenetic reader that binds to acetylated and crotonylated lysines, unlike the bromodomain which can only bind to acetylated lysines. All members of this family have been shown to be components of various complexes with roles in chromatin remodeling, histone modification, histone variant deposition, and transcriptional regulation. MLLT3 is a critical regulator of hematopoiesis with a role in maintaining the hematopoietic stem or progenitor cell (HSPC) population. Approximately 10% of acute myeloid leukemia (AML) and acute lymphocytic leukemia (ALL) patients harbor a translocation involving MLL (mixed lineage leukemia). In the context of MLL fusion patients with AML and ALL, MLL-AF9 and MLL-ENL fusions are observed in 34 and 31% of the patients, respectively. The intrinsically disordered C-terminal domain of MLLT3 (AHD, ANC1 homology domain) undergoes coupled binding and folding upon interaction with partner proteins AF4, DOT1L, BCOR, and CBX8. Backbone dynamics studies of the complexes suggest a role for dynamics in function. Inhibitors of the interaction of the intrinsically disordered AHD with partner proteins have been described, highlighting the feasibility of targeting intrinsically disordered regions. MLLT1 undergoes phase separation to enhance recruitment of the super elongation complex (SEC) and drive transcription. Mutations in MLLT1 observed in Wilms tumor patients enhance phase separation and transcription to drive an aberrant gene expression program.

Retailers often offer free shipping contingent on an order satisfying a pre-specified threshold amount (Contingent Free Shipping, CFS). As a response, customers may pad up below-threshold orders to avoid paying shipping charges. From a retailer’s standpoint, such order-padding behavior can economize logistics costs provided that customers do not engage in padding behavior that yields bubble purchases---padded orders with above-par return propensity. Bubble purchases can financially strain a retailer via increased returns handling cost. In this study, we empirically examine how the customers’ engagement in bubble purchases relates to: (i) CFS policy’s threshold and shipping fee levers; and (ii) a contextual lever---ease of product return---that is elemental to customers’ return consideration. To do so, we collaborate with a large online retailer who switched over time between multiple CFS policies. Our empirical strategy builds on the induced quasi-natural experiments by these switches, and variation in customers’ experience in processing returns. We find that, in response to our retailer’s CFS policies, customers pad 12.4\% to 28.4\% of below-threshold orders. Both policy levers considerably affect their order-padding and bubble-purchase propensity. Interestingly, the share of bubble purchases in padded orders is strongly moderated by the customers’ ease-of-return experience. In markets with a customer-friendly return process, this share varies from 8.4\% to 14.7\% and is altogether eliminated in markets with modest inconveniences in the return process. Our findings suggest managers should carefully select CFS policy terms in accordance with (and not in isolation from) their returns policy features to drive its efficacy.

Ubiquitination is one of the most prevalent forms of post-translational modifications that are important for regulating many cellular processes in eukaryotes. Deubiquitinases are proteases that hydrolyze the isopeptide or peptide bonds formed between ubiquitin and the target proteins or within a polyubiquitin chain. Deubiquitinase A (DUBA) is a deubiquitinase known to be a negative regulator of innate immune responses in humans by suppressing production of type I interferons (INF-I). Excess INF-I production has been associated with autoimmune diseases. Phosphorylation of a single serine residue at position 177 is essential for the protease activity of DUBA. The structural and mechanistic basis of DUBA activation by phosphorylation and substrate specificity is not well understood. Here, we report the backbone resonance assignments of the isoform 2 of DUBA in both non-phosphorylated and phosphorylated forms. The reported assignments form the basis for future NMR studies on the structural and dynamical properties of both active and inactive forms of DUBA.

Deubiquitinases deconjugate ubiquitin modifications from target proteins and are involved in many cellular processes in eukaryotes. The functions of deubiquitinases are regulated by post-translational modifications, mainly phosphorylation and ubiquitination. Post-translational modifications can result in subtle changes in structural and dynamic properties, which are difficult to identify but functionally important. In this work, we used NMR spectroscopy to characterize the conformational properties of the human deubiquitinase A (DUBA), a negative regulator of type I interferon. DUBA activity is regulated by phosphorylation at a single serine residue, Ser-177. We found that the catalytic rate constant of DUBA is enhanced by phosphorylation. By comparing NMR and enzyme kinetics data among different forms of DUBA with low and high activities, we concluded that a two-state equilibrium that was present only in phosphorylated DUBA is important for DUBA activity. Our results highlight the importance of defining conformational dynamics in understanding the mechanism of DUBA activation.

Bacterial peptidyl-tRNA hydrolase (Pth; EC 3.1.1.29) hydrolyzes the peptidyl-tRNAs accumulated in the cytoplasm and thereby prevents cell death by alleviating tRNA starvation. X-ray and NMR studies ofVibrio choleraePth (VcPth) and mutants of its key residues involved in catalysis show that the activity and selectivity of the protein depends on the stereochemistry and dynamics of residues H24, D97, N118, and N14. D97-H24 interaction is critical for activity because it increases the nucleophilicity of H24. The N118 and N14 have orthogonally competing interactions with H24, both of which reduce the nucleophilicity of H24 and are likely to be offset by positioning of a peptidyl-tRNA substrate. The region proximal to H24 and the lid region exhibit slow motions that may assist in accommodating the substrate. Helix α3 exhibits a slow wobble with intermediate time scale motions of its N-cap residue N118, which may work as a flypaper to position the scissile ester bond of the substrate. Overall, the dynamics of interactions between the side chains of N14, H24, D97, and N118, control the catalysis of substrate by this enzyme.

Background Accumulation of toxic peptidyl-tRNAs in the bacterial cytoplasm is averted by the action of peptidyl-tRNA hydrolase (Pth), which cleaves peptidyl-tRNA into free tRNA and peptide. NMR studies are needed for a protein homolog with a complete crystal structure, for comparison with the NMR structure of Mycobacterium tuberculosis Pth. Methods The structure and dynamics of Mycobacterium smegmatis Pth (MsPth) were characterized by NMR spectroscopy and MD simulations. The thermal stability of MsPth was characterized by DSC. Results MsPth NMR structure has a central mixed seven stranded β-sheet that is enclosed by six α-helices. NMR relaxation and MD simulations studies show that most of the ordered regions are rigid. Of the substrate binding segments, the gate loop is rigid, the base loop displays slow motions, while the lid loop displays fast timescale motions. MsPth displays high thermal stability characterized by a melting temperature of 61.71 °C. Conclusion The NMR structure of MsPth shares the canonical Pth fold with the NMR structure of MtPth. The motional characteristics for the lid region, the tip of helix α3, and the gate region, as indicated by MD simulations and NMR data, are similar for MsPth and MtPth. However, MsPth has relatively less rigid base loop and more compactly packed helices α5 and α6. The packing and the dynamic differences appear to be an important contributing factor to the thermal stability of MsPth, which is significantly higher than that of MtPth. Significance MsPth structure consolidates our understanding of the structure and dynamics of bacterial Pth proteins.

Ubiquitination is one of the most prevalent forms of post-translational modifications that are important for regulating many cellular processes in eukaryotes. Deubiquitinases are proteases that hydrolyze the isopeptide or peptide bonds formed between ubiquitin and the target proteins or within a polyubiquitin chain. Deubiquitinase A (DUBA) is a deubiquitinase known to be a negative regulator of innate immune responses in humans by suppressing production of type I interferons (INF-I). Excess INF-I production has been associated with autoimmune diseases. Phosphorylation of a single serine residue at position 177 is essential for the protease activity of DUBA. The structural and mechanistic basis of DUBA activation by phosphorylation and substrate specificity is not well understood. Here, we report the backbone resonance assignments of the isoform 2 of DUBA in both non-phosphorylated and phosphorylated forms. The reported assignments form the basis for future NMR studies on the structural and dynamical properties of both active and inactive forms of DUBA.

Background Bacterial peptidyl-tRNA hydrolase (Pth) is an essential enzyme that alleviates tRNA starvation by recycling prematurely dissociated peptidyl-tRNAs. The specificity of Pth for N-blocked-aminoacyl-tRNA has been proposed to be contingent upon conserved residue N14 forming a hydrogen bond with the carbonyl of the first peptide bond in the substrate. M71 is involved in forming a conserved hydrogen bond with N14. Other interactions facilitating this recognition are not known. Methods The structure, dynamics, and stability of the M71A mutant of Pth from Vibrio cholerae (VcPth) were characterized by X-ray crystallography, NMR spectroscopy, MD simulations and DSC. Results Crystal structure of M71A mutant was determined. In the structure, the dimer interface is formed by the insertion of six C-terminal residues of one molecule into the active site of another molecule. The side-chain amide of N14 was hydrogen bonded to the carbonyl of the last peptide bond formed between residues A196 and E197, and also to A71. The CSP profile of mutation was similar to that observed for the N14D mutant. M71A mutation lowered the thermal stability of the protein. Conclusion Our results indicate that the interactions of M71 with N14 and H24 play an important role in optimal positioning of their side-chains relative to the peptidyl-tRNA substrate. Overall, these interactions of M71 are important for the activity, stability, and compactness of the protein. Significance The work presented provides original and new structural and dynamics information that significantly enhances our understanding of the network of interactions that govern this enzyme's activity and selectivity.

The nematode Caenorhabditis elegans has two ADF (actin-depolymerizing factor)/cofilin isoforms, UNC-60A and UNC-60B, which are expressed by the unc60 gene by alternative splicing. UNC-60A has higher activity to cause net depolymerization, and to inhibit polymerization, than UNC-60B. UNC-60B, on the other hand, shows much stronger severing activity than UNC-60A. To understand the structural basis of their functional differences, we have determined the solution structures of UNC-60A and UNC-60B proteins and characterized their backbone dynamics. Both UNC-60A and UNC-60B show a conserved ADF/cofilin fold. The G-actin (globular actin)-binding regions of the two proteins are structurally and dynamically conserved. Accordingly, UNC-60A and UNC-60B individually bind to rabbit muscle ADP–G-actin with high affinities, with Kd values of 32.25 nM and 8.62 nM respectively. The primary differences between these strong and weak severing proteins were observed in the orientation and dynamics of the F-actin (filamentous actin)-binding loop (F-loop). In the strong severing activity isoform UNC-60B, the orientation of the F-loop was towards the recently identified F-loop-binding region on F-actin, and the F-loop was relatively more flexible with 14 residues showing motions on a nanosecond–picosecond timescale. In contrast, in the weak severing protein isoform UNC-60A, the orientation of the F-loop was away from the F-loop-binding region and inclined towards its own C-terminal and strand β6. It was also relatively less flexible with only five residues showing motions on a nanosecond–picosecond timescale. These differences in structure and dynamics seem to directly correlate with the differential F-actin site-binding and severing properties of UNC-60A and UNC-60B, and other related ADF/cofilin proteins.

Lignin, a major constituent of plant call wall, is a phenolic heteropolymer. It plays a major role in the development of plants and their defense mechanism against pathogens. Therefore Lignin biosynthesis is one of the critical metabolic pathways. In lignin biosynthesis, the Cinnamoyl CoA reductase is a key enzyme which catalyzes the first step in the pathway. Cinnamoyl CoA reductase provides the substrates which represent the main transitional molecules of lignin biosynthesis pathway, exhibits a high in vitro kinetic preference for feruloyl CoA. In present study, the three-dimensional model of cinnamoyl CoA reductase was constructed based on the crystal structure of Grape Dihydroflavonol 4-Reductase. Furthermore, the docking studies were performed to understand the substrate interactions to the active site of CCR. It showed that residues ARG51, ASN52, ASP54 and ASN58 were involved in substrate binding. We also suggest that residue ARG51 in CCR is the determinant residue in competitive inhibition of other substrates. This structural and docking information have prospective implications to understand the mechanism of CCR enzymatic reaction with feruloyl CoA, however the approach will be applicable in prediction of substrates and engineering 3D structures of other enzymes as well.

Major cities—including New York, Paris, and London—have implemented bike-share systems to increase the use of sustainable modes of transportation. In this chapter we discuss the operational challenges of implementing such systems and also provide design recommendations. Critical decisions when implementing bike-share systems are the number of bikes and the number of docking points. For a proposed system, these quantities are determined as a function of the imbalance in demand flow (i.e., of demand asymmetry) in different directions. We show how this asymmetry affects decisions about the number of bikes and docking points and also about the frequency with which bikes should be reallocated from full stations to empty ones. The importance for users of the accessibility to stations and their bike-availability are the key determinants of how many daily trips a system attracts and hence of that system’s optimal design. We describe an empirical study that determines user behavior in a central Parisian bike-share system and then suggest an alternate design which can increase the number of trips by almost 29 % for the same amount of resources in number of bikes based on user behavior parameters that we estimate.

Background Myocardial extracellular volume (ECV) quantification by cardiovascular magnetic resonance (CMR) T1 mapping technique has shown great promises in detecting diffuse fibrosis and interstitial diseases of the myocardium. In hypertensive and left ventricle hypertrophy (LVH) patients, increased ECV has been found to be associated with impaired myocardial strain, which is an early indicator of cardiac dysfunction. We hypothesized that in a heterogeneous patient population, ECV was significantly associated with myocardial strain, on the global and the more localized segmental bases.

The actin filament dynamics in nematode, Caenorhabditis elegans, is regulated by differential activity of two proteins UNC-60A and UNC-60B. UNC-60A exhibits strong pointed end depolymerization on C. elegans actin (Ce-actin), strong inhibition of polymerization, strong monomer sequestering activity, weak severing activity, and low affinity for F-actin binding, while UNC-60B exhibits strong pointed end depolymerization on rabbit muscle actin, strong severing activity, and high affinity for F-actin binding. Structural characterization of these proteins will help to understand (1) molecular mechanism of actin dynamics regulation and (2) the differential activity of these proteins. Here, we report (1)H, (13)C, and (15)N chemical shift assignments of these two proteins as determined by heteronuclear NMR experiments (at pH 6.5 and temperature 298 K).

This paper compares the financial and environmental performance of two revenue models for the online retailing of groceries: the per-order model, where customers pay for each delivery; and the subscription model, where customers pay a set fee and receive free deliveries. We build a stylized model that incorporates (i) customers with ongoing uncertain grocery needs and who choose between shopping offline or online and (ii) an online retailer that makes deliveries through a proprietary distribution network. We find that subscription incentivizes smaller and more frequent grocery orders, which reduces food waste and creates more value for the customer; the result is higher retailer revenues, lower grocery costs, and potentially higher adoption rates. These advantages are countered by greater delivery-related travel and expenses, which are moderated by area geography and routing-related scale economies. Subscription also leads to lower food waste-related emissions but to higher delivery-related emissions. Ceteris paribus, the per-order model is preferable for higher-margin retailers with higher-consumption product assortments that are sold in sparsely populated markets spread over large, irregular areas with high delivery costs. Geographic and demographic data indicate that the subscription model is almost always environmentally preferable because lower food waste emissions dominate higher delivery emissions.