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The selective targeting of protein-protein interactions remains a significant determinant for the proper modulation and regulation of cell apoptosis. Prototypic galectins such as human galectin-7 (GAL-7) are characterized by their ability to form homodimers that control the molecular fate of a cell by mediating subtle yet critical glycan-dependent interactions between pro- and anti-apoptotic molecular partners. Altering the structural architecture of GAL-7 can therefore result in resistance to apoptosis in various human cancer cells, further illustrating its importance in cell survival. In this study, we used a combination of biophysical and cellular assays to illustrate that binding of a water-soluble meso-tetraarylporphyrin molecule to GAL-7 induces protein oligomerization and modulation of GAL-7-induced apoptosis in human Jurkat T cells. Our results suggest that the integrity of the GAL-7 homodimer architecture is essential for its molecular function, in addition to providing an interesting porphyrin binding modulator for controlling apoptosis in mammalian cells.

Nucleation is one of the least understood steps of microtubule dynamics. It is a kinetically unfavorable process that is templated in the cell by the γ-tubulin ring complex or by preexisting microtubules; it also occurs in vitro from pure tubulin. Here we study the nucleation inhibition potency of natural or artificial proteins in connection with their binding mode to the longitudinal surface of α- or β-tubulin. The structure of tubulin-bound CopN, a Chlamydia protein that delays nucleation, suggests that this protein may interfere with two protofilaments at the (+) end of a nucleus. Designed ankyrin repeat proteins that share a binding mode similar to that of CopN also impede nucleation, whereas those that target only one protofilament do not. In addition, an αRep protein predicted to target two protofilaments at the (−) end does not delay nucleation, pointing to different behaviors at both ends of the nucleus. Our results link the interference with protofilaments at the (+) end and the inhibition of nucleation.

Introduction The aim of this study is to assess the prevalence of tubal histopathological abnormalities (serous tubal intraepithelial carcinoma STIC and p53 signatures) and the prevalence of perioperative and postoperative complications related to opportunistic laparoscopic salpingectomy in a low risk population. Materials and Methods In this observational prospective cohort, prophylactic bilateral salpingectomy during benign laparoscopic hysterectomy was systematically performed in 100 consecutive women. Peri- and postoperative complications were registered. Duration of salpingectomy and post-salpingectomy blood loss were also measured. Histopathological and immunohistochemical analysis with anti-p53 antibody were performed on the whole fallopian tubes according to a specific and validated protocol. Results Laparoscopic salpingectomy was always possible without any peri- or postoperative complication attributable to the salpingectomy itself. The mean duration was 428 seconds (354 – 596) and the blood loss was 9 cm3 (2 – 15). Using histopathological and immunohistochemical assessment with anti-p53 antibody on 199 fallopian tubes (99 bilateral salpingectomies and one unilateral salpingectomy because of previous salpingectomy for ectopic pregnancy), there was a prevalence of 5.52% (11/199) of p53 signatures. No STIC were observed and no associated cancer. Conclusions Laparoscopic salpingectomy is both feasible and innocuous during benign hysterectomy. Meticulous histopathologic examination of the tubes may reveal specific abnormalities.

Streptococcus equi is a horse pathogen belonging to Lancefield group C. Infection by S. equi ssp. equi causes strangles, a serious and highly contagious disease of the upper respiratory tract. S. equi ssp. equi secretes a fibronectin (Fn)-binding protein, FNE, that does not contain cell wall-anchoring motifs. FNE binds to the gelatin-binding domain (GBD) of Fn, composed of the motifs 6FI12FII789FI. FNE lacks the canonical Fn-binding peptide repeats observed in many microbial surface components recognizing adhesive matrix molecules. We found that the interaction between FNE and the human GBD is mediated by the binding of the disordered C-terminal region (residues 208–262) of FNE to the 789FI GBD subfragment. The crystal structure of FNE showed that it is similar to the minor pilus protein Spy0125 of Streptococcus pyogenes, found at the end of pilus polymers and responsible for adhesion. FNE and Spy0125 both have a superimposable internal thioester bond between highly conserved Cys and Gln residues. Small-angle X-ray scattering of the FNE–789FI complex provided a model that aligns the C-terminal peptide of FNE with the E-strands of the FI domains, adopting the β-zipper extension model observed in previous structures of microbial surface components recognizing adhesive matrix molecule adhesion peptides bound to FI domains. Database The coordinates of the FNE–αREP3 complex have been deposited at the Protein Data Bank under the code 4PFG. Structured digital abstract GBD and FNE bind by isothermal titration calorimetry (View interaction) GBD 789FI and FNE bind by isothermal titration calorimetry (View interaction) FNE-CT and GBD 789FI bind by isothermal titration calorimetry (View interaction) GBD and FNE-CT bind by isothermal titration calorimetry (View interaction) FNE and GBD 789FI bind by molecular sieving (View interaction) FNE-CT binds to GBD 789FI by pull down (View interaction) FNE and GBD 789FI bind by x ray scattering (View interaction) GBD and FNE physically interact by fluorescence polarization spectroscopy (View interaction) collagen and GBD bind by fluorescence polarization spectroscopy (View interaction)

A new generation of artificial proteins, derived from alpha-helicoidal HEAT-like repeat protein scaffolds (alpha Rep), was previously characterized as an effective source of intracellular interfering proteins. In this work, a phage-displayed library of alpha Rep was screened on a region of HIV-1 Gag polyprotein encompassing the C-terminal domain of the capsid, the SP1 linker and the nucleocapsid. This region is known to be essential for the late steps of HIV-1 life cycle, Gag oligomerization, viral genome packaging and the last cleavage step of Gag, leading to mature, infectious virions. Two strong alpha Rep binders were isolated from the screen, alpha Rep4E3 (32 kDa; 7 internal repeats) and alpha Rep9A8 (28 kDa; 6 internal repeats). Their antiviral activity against HIV-1 was evaluated in VLP-producer cells and in human SupT1 cells challenged with HIV-1. Both alpha Rep4E3 and alpha Rep9A8 showed a modest but significant antiviral effects in all bioassays and cell systems tested. They did not prevent the proviral integration reaction, but negatively interfered with late steps of the HIV-1 life cycle: alpha Rep4E3 blocked the viral genome packaging, whereas alpha Rep9A8 altered both virus maturation and genome packaging. Interestingly, SupT1 cells stably expressing alpha Rep9A8 acquired long-term resistance to HIV-1, implying that alpha Rep proteins can act as antiviral restriction-like factors.

Summary The dengue virus (DENV) complex is composed of four distinct but serologically related flaviviruses, which together cause the present-day most important emerging viral disease. Although DENV infection induces lifelong immunity against viruses of the same serotype, the antibodies raised appear to contribute to severe disease in cases of heterotypic infections. Understanding the mechanisms of DENV neutralization by antibodies is, therefore, crucial for the design of vaccines that simultaneously protect against all four viruses. Here, we report a comparative, high-resolution crystallographic analysis of an "A-strand" murine monoclonal antibody, Mab 4E11, in complex with its target domain of the envelope protein from the four DENVs. Mab 4E11 is capable of neutralizing all four serotypes, and our study reveals the determinants of this cross-reactivity. The structures also highlight the mechanism by which A-strand Mabs disrupt the architecture of the mature virion, inducing premature fusion loop exposure and concomitant particle inactivation.

Breaking ties: The antitumour protein, neocarzinostatin (NCS), is one of the few drug-carrying proteins used in human therapeutics. However, the presence of disulfide bonds limits this protein's potential development for many applications. This study describes a generic directed-evolution approach starting from NCS-3.24 (shown in the figure complexed with two testosterone molecules) to engineer stable disulfide-free NCS variants suitable for a variety of purposes, including intracellular applications.The chromoprotein neocarzinostatin (NCS) has been intensively studied for its antitumour properties. It has recently been redesigned as a potential drug-carrying scaffold. A potential limit of this protein scaffold, especially for intracellular applications, is the presence of disulfide bonds. The objective of this work was to create a disulfide-free NCS-derived scaffold. A generic targeted approach was developed by using directed evolution methods. As a starting point we used a previously engineered NCS variant in which a hapten binding site had been created. A library was then generated in which cysteine Cys88 and Cys93 and neighbouring residues were randomly substituted. Variants that preserved the hapten binding function were selected by phage display and further screened by colony filtration methods. Several sequences with common features emerged from this process. The corresponding proteins were expressed, purified and their biophysical properties characterised. How these selected sequences rescued folding ability and stability of the disulfide-free protein was carefully examined by using calorimetry and the results were interpreted with molecular simulation techniques.

A copper(II) cofactor coupled to a testosterone anchor, copper(II)-(5-(Piperazin-1-yl)-1,10-phenanthroline)testosterone-17-hemisuccinamide (10) was synthesized and associated with a neocarzinostatin variant, NCS-3.24 (KD =3 μm), thus generating a new artificial metalloenzyme by following a "Trojan horse" strategy. Interestingly, the artificial enzyme was able to efficiently catalyze the Diels-Alder cyclization reaction of cyclopentadiene (1) with 2-azachalcone (2). In comparison with what was observed with cofactor 10 alone, the artificial enzymes favored formation of the exo products (endo/exo ratios of 84:16 and 62:38, respectively, after 12 h). Molecular modeling studies assigned the synergy between the copper complex and the testosterone (KD =13 μm) moieties in the binding of 10 to good van der Waals complementarity. Moreover, by pushing the modeling exercise to its limits, we hypothesize on the molecular grounds that are responsible for the observed selectivity.

A new zinc(II)-cofactor coupled to a testosterone anchor, zinc(II)- N , N -bis(2-pyridylmethyl)-1,3-diamino-propa-2-ol- N ′(17′-succinimidyltestosterone) (Zn-Testo-BisPyPol) 1 -Zn has been synthesized and fully characterized. It has been further associated with a neocarzinostatin variant, NCS-3.24, to generate a new artificial metalloenzyme following the so-called ‘Trojan horse’ strategy. This new 1 -Zn-NCS-3.24 biocatalyst showed an interesting catalytic activity as it was found able to catalyze the hydrolysis of the RNA model HPNP with a good catalytic efficiency ( k cat / K M = 13.6 M −1 s −1 at pH 7) that places it among the best artificial catalysts for this reaction. Molecular modeling studies showed that a synergy between the binding of the steroid moiety and that of the BisPyPol into the protein binding site can explain the experimental results, indicating a better affinity of 1 -Zn for the NCS-3.24 variant than testosterone and testosterone-hemisuccinate themselves. They also show that the artificial cofactor entirely fills the cavity, the testosterone part of 1 -Zn being bound to one the two subdomains of the protein providing with good complementarities whereas its metal ion remains widely exposed to the solvent which made it a valuable tool for the catalysis of hydrolysis reactions, such as that of HPNP. Some possible improvements in the ‘Trojan horse’ strategy for obtaining better catalysts of selective reactions will be further studied.

Diaphragmatic paralysis, a difficult diagnosis in the pediatric age group, has classically been made by fluoroscopy or B-mode ultrasound. We report our experience with TM-mode exploration. Twenty-seven patients suspected to have diaphragmatic paralysis were examined by means of inspiratory and expiratory chest radiography, fluoroscopy and B-mode ultrasound. The diaphragmatic echo was recorded on TM-tracing during spontaneous breathing using coronal oblique scans. Direction, excursion and the pattern of the transition between inspiration and expiration were analysed. In 7 patients examination was normal and TM mode demonstrated movement of normal direction and excursion with a sharp aspect of the transition zone. Diaphragmatic paralysis was present in 11 patients: unilateral in 9 and bilateral in 2 cases. TM mode demonstrated paradoxical movement, reduced excursion and a smooth transition zone. In 9 patients with diaphragmatic dysfunction TM mode demonstrated movement in the normal direction but with reduced excursion and a smooth transition zone. Compared to other imaging modalities, TM-mode records diaphragmatic movements more objectively. It can identify direction of the movement even if they are fast and of weak amplitude and in the case of bilateral paralysis. TM can differentiate paralysis from dysfunction. Moreover, this low-cost, non-irradiating made of imaging can be performed at the bedside and is available on all basic devices.

Dengue is a re-emerging viral disease, affecting approx. 100 million individuals annually. The monoclonal antibody mAb4E11 neutralizes the four serotypes of the dengue virus, but not other flaviviruses. Its epitope is included within the highly immunogenic domain 3 of the envelope glycoprotein E. To understand the favorable properties of recognition between mAb4E11 and the virus, we recreated the genetic events that led to mAb4E11 during an immune response and performed an alanine scanning mutagenesis of its third hypervariable loops (H-CDR3 and L-CDR3). The affinities between 16 mutant Fab fragments and the viral antigen (serotype 1) were measured by a competition ELISA in solution and their kinetics of interaction by surface plasmon resonance. The diversity and junction residues of mAb4E11 (D segment; V(H)-D, D-J(H) and V(L)-J(L) junctions) constituted major hotspots of interaction energy. Two residues from the D segment (H-Trp96 and H-Glu97) provided85% of the free energy of interaction and were highly accessible to the solvent in a three-dimensional model of mAb4E11. Changes of residues (L-Arg90 and L-Pro95) that statistically do not participate in the contacts between antibodies and antigens but determine the structure of L-CDR3, decreased the affinity between mAb4E11 and its antigen. Changes of L-Pro95 and other neutral residues strongly decreased the rate of association, possibly by perturbing the topology of the electrostatic field of the antibody. These data will help to improve the properties of mAb4E11 for therapeutic applications and map its epitope precisely.

We report on 56 children with sclerosing cholangitis (SC) seen between 1972 and 1992. The first symptoms occurred at a mean age of 3.7 years; 15 infants had neonatal cholestatic jaundice. At diagnosis, cholestatic jaundice was present in 25 children, hepatomegaly in 54, splenomegaly in 41, and ascites in 12. Serum alkaline phosphatase activity was increased in 49 patients and γ-glutamyltransferase activity in all patients tested. Most often the histopathologic findings were extensive portal fibrosis and neoductular proliferation. Cholangiography showed abnormal intrahepatic bile ducts in all children and abnormal extrahepatic bile ducts in 35 (63%). The children were separated into three groups: (1) those with SC of neonatal onset (27%); (2) those with SC of postneonatal onset associated with another disease (55%)—histiocytosis X in 14 children, immunodeficiency syndromes in 8, chronic inflammatory bowel disease or autoimmune hepatitis in 8, and congenital psoriasis in 1; and (3) those with SC of postneonatal onset without an associated disease (18%). Biliary cirrhosis was present in all but three children after 6 months to 19.3 years of follow-up. Eleven children died of portal hypertension or liver failure, and six died of a complication related to the associated disease. Fifteen children had liver transplantation; 11 of these are alive 6 months to 61/2 years later without recurrence of SC. The overall estimated median survival time of children with SC was 10 years from clinical onset. These results indicate that SC should be suspected in all children with a chronic cholestatic disease and increased serum γ-glutamyl transferase activity, especially when diseases known to be associated with SC are present. The prognosis is poor, but liver transplantation should be considered except in those with severe immunodeficiency syndromes. (J P EDIATR 1994;124:49-56)

Thymic hemorrhage related to coagulopathy by vitamin K deficiency is a rare condition. We report a case in a 4-week-old boy presenting with acute onset of respiratory distress and anemia. Ultrasound examination of a compressive anterior mediastinal mass established the diagnosis of thymic hemorrhage and allowed us to follow resolution under medical treatment.