Insights into substrate recognition and export tunnel preferences in the efflux transporter AcrB.

In Escherichia coli AcrB is a major multidrug exporter, which confers the bacterium resistance to many antibiotics with diverse structural and chemical proprieties. Studies have identified three possible tunnels (or channels) within AcrB that different substrates use before reaching the distal pocket, from which they are subsequently extruded. Recently, we reported that mutations in the AcrB gate loop may affect the conformational change kinetics involved in substrate export rather than directly affecting molecular interactions with this loop, and we highlighted the distinct export tunnel preferences between erythromycin and doxorubicin.

Evolutions in cardiac and gonadal ultra-structure during a "cycle" of androgenic anabolic abuse in adult male mice.

Background: The importance of the present study comes from the lack of sufficient information about the reversibility of the potential histopathological alterations which may result from anabolic androgenic drugs abuse by "Cycling" protocol. So, the aim of this study is to explore the negative effects of Deca-Durabolin abuse in cardiac and gonadal ultra-structures during an administration cycle.

Methods: For our purpose, study was performed on 40 male adult mices.

IMU-based sensor-to-segment multiple calibration for upper limb joint angle measurement-a proof of concept.

A lot of attention has been paid to wearable inertial sensors regarded as an alternative solution for outdoor human motion tracking. Relevant joint angles can only be calculated from anatomical orientations, but they are negatively impacted by soft tissue artifact (STA) defined as skin motion with respect to the underlying bone; the accuracy of measured joint angle during movement is affected by the ongoing misalignment of the sensor. In this work, a new sensor-to-segment calibration using inertial measurement units is proposed.

New insights into the structural and functional involvement of the gate loop in AcrB export activity.

AcrB is a major multidrug exporter in Escherichia coli and other Gram-negative bacteria. Its gate loop, located between the proximal and the distal pockets, have been reported to play important role in the export of many antibiotics. This loop location, rigidity and interactions with substrates have led recent reports to suggest that AcrB export mechanism operates in a sequential manner.

On the Ca binding and conformational change in EF-hand domains: Experimental evidence of Ca-saturated intermediates of N-domain of calmodulin.

Double mutation of Q41L and K75I in the N-domain of calmodulin (N-Cam) stabilizes the closed form of N-Cam such that binding of Ca in solution no longer triggers a conformational change to the open form, and its Ca binding affinity decreases dramatically. To further investigate the solvation effects on the structure, Ca binding affinity and conformational dynamics of this N-Cam double mutant in the Ca saturated state, we solved its X-ray structure. Surprisingly, the structure revealed an open conformation of the domain which contradicts its closed conformation in solution.

Structures of Gate Loop Variants of the AcrB Drug Efflux Pump Bound by Erythromycin Substrate.

Gram-negative bacteria such as E. coli use tripartite efflux pumps such as AcrAB-TolC to expel antibiotics and noxious compounds. A key feature of the inner membrane transporter component, AcrB, is a short stretch of residues known as the gate/switch loop that divides the proximal and distal substrate binding pockets.

The Cardiac Stress Response Factor Ms1 Can Bind to DNA and Has a Function in the Nucleus.

Ms1 (also known as STARS and ABRA) has been shown to act as an early stress response gene in processes as different as hypertrophy in skeletal and cardiac muscle and growth of collateral blood vessels. It is important for cardiac development in zebrafish and is upregulated in mouse models for cardiac hypertrophy as well as in human failing hearts. Ms1 possesses actin binding sites at its C-terminus and is usually found in the cell bound to actin filaments in the cytosol or in sarcomeres.

Electrostatics effects on Ca(2+) binding and conformational changes in EF-hand domains: Functional implications for EF-hand proteins.

Mutations of Gln41 and Lys75 with nonpolar residues in the N-terminal domain of calmodulin (N-Cam) revealed the importance of solvation energetics in conformational change of Ca(2+) sensor EF-hand domains. While in general these domains have polar residues at these corresponding positions yet the extent of their conformational response to Ca(2+) binding and their Ca(2+) binding affinity can be different from N-Cam. Consequently, here we address the charge state of the polar residues at these positions.

Prevalence of bovine theileriosis in North Central region of Algeria by real-time polymerase chain reaction with a note on its distribution.

To determine the presence and distribution of bovine theileriosis in the North Central region of Algeria, 358 DNA samples and 359 blood smears were analyzed from nine provinces. Theileria DNA extracted from cattle blood was amplified by fluorescence resonance energy transfer polymerase chain reaction (FRET-PCR). Blood smears were examined for Theileria piroplasms by microscopical examination (ME) of Giemsa-stained slides.

Structure of an atypical periplasmic adaptor from a multidrug efflux pump of the spirochete Borrelia burgdorferi.

Periplasmic adaptor proteins are essential components of bacterial tripartite multidrug efflux pumps. Here we report the 2.35 Å resolution crystal structure of the BesA adaptor from the spirochete Borrelia burgdorferi solved using selenomethionine derivatized protein.

Making ends meet: the importance of the N- and C-termini for the structure, stability, and function of the third SH3 domain of CIN85.

SH3 domains are common structure, interaction, and regulation modules found in more than 200 human proteins. In this report, we studied the third SH3 domain from the human CIN85 adaptor protein, which plays an important role in both receptor tyrosine kinase downregulation and phosphatidylinositol 3 kinase inhibition. The structure of this domain includes an additional 90° kink after the last canonical β-strand and features unusual interactions between the termini well outside the boundaries of the standard SH3 domain definition.

Novel insights into the mechanisms of CIN85 SH3 domains binding to Cbl proteins: solution-based investigations and in vivo implications.

CIN85 is a multifunctional protein that plays key roles in endocytic down-regulation of receptor tyrosine kinases, apoptosis, cell adhesion, and cytoskeleton rearrangement. Its three SH3 domains (CIN85A, CIN85B, and CIN85C) allow it to recruit multiple binding partners. To understand the manifold interactions of CIN85, we present a detailed high-resolution solution structural study of CIN85A and CIN85B binding to proline-arginine peptides derived from the cognate ligands Cbl and Cbl-b.

Myosin binding protein C positioned to play a key role in regulation of muscle contraction: structure and interactions of domain C1.

Myosin binding protein C (MyBP-C) is a thick filament protein involved in the regulation of muscle contraction. Mutations in the gene for MyBP-C are the second most frequent cause of hypertrophic cardiomyopathy. MyBP-C binds to myosin with two binding sites, one at its C-terminus and another at its N-terminus.

Structure, dynamics, and binding thermodynamics of the v-Src SH2 domain: implications for drug design.

SH2 domains provide fundamental recognition sites in tyrosine kinase-mediated signaling pathways which, when aberrant, give rise to disease states such as cancer, diabetes, and immune deficiency. Designing specific inhibitors that target the SH2 domain-binding site, however, have presented a major challenge. Despite well over a decade of intensive research, clinically useful SH2 domain inhibitors have yet to become available.

Molecular plasticity of beta-catenin: new insights from single-molecule measurements and MD simulation.

The multifunctional protein, beta-catenin, has essential roles in cell adhesion and, through the Wnt signaling pathway, in controlling cell differentiation, development, and generation of cancer. Could distinct molecular forms of beta-catenin underlie these two functions? Our single-molecule force spectroscopy of armadillo beta-catenin, with molecular dynamics (MD) simulation, suggests a model in which the cell generates various forms of beta-catenin, in equilibrium. We find beta-catenin and the transcriptional factor Tcf4 form two complexes with different affinities.

The effects of arm position on onset and duration of axillary brachial plexus block.

Background: We assessed the effects of arm position after block performance on success rate, onset time, and duration of axillary block (AXB).

Methods: After performing AXB, patients were randomized into two groups: group adduction in which the arm was immediately placed in adduction along the body and group abduction in which the arm remained in abduction. These positions were maintained until the block was achieved.

Dissecting the N-terminal myosin binding site of human cardiac myosin-binding protein C. Structure and myosin binding of domain C2.

Myosin-binding protein C (MyBP-C) binds to myosin with two binding sites, one close to the N terminus and the other at the C terminus. Here we present the solution structure of one part of the N-terminal binding site, the third immunoglobulin domain of the cardiac isoform of human MyBP-C (cC2) together with a model of its interaction with myosin. Domain cC2 has the beta-sandwich structure expected from a member of the immunoglobulin fold.

Survey of the year 2005: literature on applications of isothermal titration calorimetry.

Isothermal titration calorimetry (ITC) can provide a full thermodynamic characterization of an interaction. Its usage does not suffer from constraints of molecular size, shape or chemical constitution. Neither is there any need for chemical modification or attachment to solid support.

Interaction energy decomposition in protein-protein association: a quantum mechanical study of barnase-barstar complex.

Protein-protein interactions are very important in the function of a cell. Computational studies of these interactions have been of interest, but often they have utilized classical modelling techniques. In recent years, quantum mechanical (QM) treatment of entire proteins has emerged as a powerful approach to study biomolecular systems.

[The post-traumatic pancreatitis: about four cases].

The post-traumatic pancreatitis is the main reason of mortality in the traumatisms of the pancreas, its concurrence is related to the lesions of the pancreatic channels. It represents only 1% of the pancreatitis. In a descriptive retrospective study, four cases of post-traumatic pancreatitis are described.

[Cerebellum abscess: first demonstration of undiagnosed infective endocarditis in an adult with corrected transposition arteries].

Neurological complications occur in approximately 30% of all patients with infective endocarditis and represent a major factor associated with an increased mortality rate. Third of these complications is represented by cerebral embolism, followed by mycotic aneurysm, meningitis or meningoencephalitis. Brain abscesses are rare; their localization to the cerebellum is exceptional.

Survey of the year 2004: literature on applications of isothermal titration calorimetry.

The market for commercially available isothermal titration calorimeters continues to grow as new applications and methodologies are developed. Concomitantly the number of users (and abusers) increases dramatically, resulting in a steady increase in the number of publications in which isothermal titration calorimetry (ITC) plays a role. In the present review, we will focus on areas where ITC is making a significant contribution and will highlight some interesting applications of the technique.