Effects of low frequency ultrasound on some properties of fibrinogen and its plasminolysis

<p>Abstract</p> <p>Background</p> <p>Pharmacological thrombolysis with streptokinase, urokinase or tissue activator of plasminogen (t-PA), and mechanical interventions are frequently used in the treatment of both arterial and venous thrombotic diseases. It has been previously reported that application of ultrasound as an adjunct to thrombolytic therapy offers unique potential to improve effectiveness. However, little is known about effects of the ultrasound on proteins of blood coagulation and fibrinolysis. Here, we investigated the effects of the ultrasound on fibrinogen on processes of coagulation and fibrinogenolysis in an <it>in vitro </it>system.</p> <p>Results</p> <p>Our study demonstrated that low frequency high intensity pulse ultrasound (25.1 kHz, 48.4 W/cm2, duty 50%) induced denaturation of plasminogen and t-PA and fibrinogen aggregates formation <it>in vitro</it>. The aggregates were characterized by the loss of clotting ability and a greater rate of plasminolysis than native fibrinogen. We investigated the effect of the ultrasound on individual proteins. In case of plasminogen and t-PA, ultrasound led to a decrease of the fibrinogenolysis rate, while it increased the fibrinogenolysis rate in case of fibrinogen. It has been shown that upon ultrasound treatment of mixture fibrinogen or fibrin with plasminogen, t-PA, or both, the rate of proteolytic digestion of fibrin(ogen) increases too. It has been shown that summary effect on the fibrin(ogen) proteolytic degradation under the conditions for combined ultrasound treatment is determined exclusively by effect on fibrin(ogen).</p> <p>Conclusions</p> <p>The data presented here suggest that among proteins of fibrinolytic systems, the fibrinogen is one of the most sensitive proteins to the action of ultrasound. It has been shown <it>in vitro </it>that ultrasound induced fibrinogen aggregates formation, characterized by the loss of clotting ability and a greater rate of plasminolysis than native fibrinogen in different model systems and under different mode of ultrasound treatment. Under ultrasound treatment of plasminogen and/or t-PA in the presence of fibrin(ogen) the stabilizing effect fibrin(ogen) on given proteins was shown. On the other hand, an increase in the rate of fibrin(ogen) lysis was observed due to both the change in the substrate structure and promoting of the protein-protein complexes formation.</p

Transcriptome Analysis in Tardigrade Species Reveals Specific Molecular Pathways for Stress Adaptations

Tardigrades have unique stress-adaptations that allow them to survive extremes of cold, heat, radiation and vacuum. To study this, encoded protein clusters and pathways from an ongoing transcriptome study on the tardigrade Milnesium tardigradum were analyzed using bioinformatics tools and compared to expressed sequence tags (ESTs) from Hypsibius dujardini, revealing major pathways involved in resistance against extreme environmental conditions. ESTs are available on the Tardigrade Workbench along with software and databank updates. Our analysis reveals that RNA stability motifs for M. tardigradum are different from typical motifs known from higher animals. M. tardigradum and H. dujardini protein clusters and conserved domains imply metabolic storage pathways for glycogen, glycolipids and specific secondary metabolism as well as stress response pathways (including heat shock proteins, bmh2, and specific repair pathways). Redox-, DNA-, stress- and protein protection pathways complement specific repair capabilities to achieve the strong robustness of M. tardigradum. These pathways are partly conserved in other animals and their manipulation could boost stress adaptation even in human cells. However, the unique combination of resistance and repair pathways make tardigrades and M. tardigradum in particular so highly stress resistant

Дикетоны природного происхождения как потенциальные ковалентные лиганды белков SARS-CoV-2: исследование in silico методом докинга

Our computer-aided protein-ligand docking test using Autodock Vina software allowed to reveal the potential of few α- and β-diketones from plants and alternative living organisms as covalent ligands for few proteins of coronavirus SARS-CoV-2 – a causative agent of COVID-19. It has been established that values for energy of binding (docking score, Ebind, kcal/mol) less than –7.5 and for distances of ligands’ carbonyl groups to side chain nitrogens of arginine residues of some coronaviral enzymes within 0.4 nm have been true for β-diketones 6-gingerdione (Pubchem code CID162952), 8-gingerdione (CID14440537), tetrahydrocurcumine (CID124072) as well as α-diketone wallitaxane E (CID132967478). The in silico revealed interactions are interesting to be verified in vitro and they point out a possibility of investigation of the compounds and related natural materials as tools for struggle against coronaviral infections.Компьютерный докинг, проведенный с использованием программы Autodock Vina, позволил выявить потенциал нескольких α- и β-дикетонов растений и других природных объектов в качестве ковалентных лигандов ряда белков коронавируса SARS-CoV-2 – возбудителя COVID-19. Выявлено, что энергией связывания (docking score, Ebind, ккал/мол) менее –7,5 с колоколизацией карбонильных групп на расстоянии не более 0,4 нм от атомов азота боковой цепи остатков аргинина белков коронавируса. β-Дикетоны 6-гингердион (код структуры по базе данных Pubchem CID162952), 8-гингердион (CID14440537), тетрагидрокуркумин (CID124072), а также α-дикетон валлитаксан E (CID132967478) обладали такими свойствами. Выявленные in silico взаимодействия указывают на возможность обнаружения их в эксперименте и исследования этих веществ или содержащих их природных материалов как средств борьбы с короновирусной инфекцией

Multi‐scale ensemble properties of the Escherichia coli RNA degradosome

Abstract: In organisms from all domains of life, multi‐enzyme assemblies play central roles in defining transcript lifetimes and facilitating RNA‐mediated regulation of gene expression. An assembly dedicated to such roles, known as the RNA degradosome, is found amongst bacteria from highly diverse lineages. About a fifth of the assembly mass of the degradosome of Escherichia coli and related species is predicted to be intrinsically disordered – a property that has been sustained for over a billion years of bacterial molecular history and stands in marked contrast to the high degree of sequence variation of that same region. Here, we characterize the conformational dynamics of the degradosome using a hybrid structural biology approach that combines solution scattering with ad hoc ensemble modelling, cryo‐electron microscopy, and other biophysical methods. The E. coli degradosome can form punctate bodies in vivo that may facilitate its functional activities, and based on our results, we propose an electrostatic switch model to account for the propensity of the degradosome to undergo programmable puncta formation

Синтез новых тиазоло[3,2-а]пиримидинов и in silico анализ их биоактивности

An effective method of synthesis thiazolo[3,2-a]pyrimidine derivatives was developed and the compounds with n-pentyl or β-acetoxycyclopropyl as well as fluorescent benzo[f]coumarin substituents were obtained with yields 60 % and more. Using computational (in silico) approaches we demonstrated the ability of the obtained compounds to permeate lipid bilayer as well as their affinity to some protein kinases (compounds 4 and 6 bind with a protein kinase AKT1 with PDB code 3о96; Autodock Vina-computed energy of binding (Ebind) values were -10.9 and -10.6 kcal/mol, respectively), acethylcholine esterase and some human cytochromes P450 (for P450 3A4, pdb 5vcd, Ebind -12.3 kcal/mol).Разработан эффективный метод получения и синтезированы новые тиазоло[3,2-a]пиримидины, содержащие н-пентановый или β-гидроксициклопропановый, а также флуоресцирующий бензо[f]кумариновый заместители с выходами более 60 %. Компьютерными методами (in silico) показана способность полученных соединений проникать через липидный бислой и оценено их сродство к ряду протеинкиназ (соединения 4 и 6 связываются с протеинкиназой AKT1 с кодом PDB 3о96; величины, рассчитываемые программой Autodock Vina энергии связывания (Ebind), составили: -10,9 и -10,6 ккал/моль), ацетилхолинэстеразе и цитохромам P450 человека (для цитохрома P450 3A4, pdb 5vcd, Ebind -12,3 ккал/моль)

Analysis of the natively unstructured RNA/protein-recognition core in the Escherichia coli RNA degradosome and its interactions with regulatory RNA/Hfq complexes.

The RNA degradosome is a multi-enzyme assembly that plays a central role in the RNA metabolism of Escherichia coli and numerous other bacterial species including pathogens. At the core of the assembly is the endoribonuclease RNase E, one of the largest E. coli proteins and also one that bears the greatest region predicted to be natively unstructured. This extensive unstructured region, situated in the C-terminal half of RNase E, is punctuated with conserved short linear motifs that recruit partner proteins, direct RNA interactions, and enable association with the cytoplasmic membrane. We have structurally characterized a subassembly of the degradosome-comprising a 248-residue segment of the natively unstructured part of RNase E, the DEAD-box helicase RhlB and the glycolytic enzyme enolase, and provide evidence that it serves as a flexible recognition centre that can co-recruit small regulatory RNA and the RNA chaperone Hfq. Our results support a model in which the degradosome captures substrates and regulatory RNAs through the recognition centre, facilitates pairing to cognate transcripts and presents the target to the ribonuclease active sites of the greater assembly for cooperative degradation or processing

In silico анализ взаимодействия соединений, содержащих фотоактивируемые группы, с ферментами CYP7 человека

In silico analysis of “protein-ligand” complexes of human CYP7 enzymes with modified borondipyrrome-tene (BODIPY) and steroids, containing photo-activated crosslinking groups, wasperformed in order to identify structural peculiarities of their interaction. It was found that BODIPY molecules and DHEA derivative with diazirine group are able to bind tightly with human steroid-hydroxylases. Binding affinity is comparable with corresponding values for essential ligands of the enzymes. Binding mode of the modified steroid corresponds to the binding mode of essential CYP7 ligands, so formation of hydroxylated products is possible. It was found that presence of both diazirine and NBD groups in a molecule significantly increases affinity of the compound in case of CYP7A1 and, especially, CYP7B1. Amino acid residues, located in a close proximity with photo-activated groups were detected, that can form covalent adducts with them. The obtained results can shed light on the mechanism of interaction of the compounds with recombinant human CYP7 enzymes in vitro. The results can also be used for the identification of modified amino acids of the proteins that are formed under photoactivation of the compounds in vitro.С целью выявления структурных особенностей взаимодействия ферментов CYP7 человека с производными бордипирометена (BODIPY) и стероидов, содержащих фотоактивируемые сшивающие группы, проведен in silico анализ комплексов «белок-лиганд». Показано, что модифицированные молекулы BODIPY, а также производное дегидроэпиандростерона с диазириновой группой способны связываться в активном центре стероид-гидроксилаз человека с аффинностью, сравнимой с соответствующими величинами, рассчитанными для природных субстратов этих ферментов. При этом геометрия комплекса «фермент-лиганд» для модифицированного стероида в активном центре также соответствует геометрии комплексов CYP7 со своими природными лигандами, что указывает на возможность образования гидроксилированных продуктов реакции - меченых аналогов биометаболитов. Показано, что наличие одновременно диазириновой и 7-нитробензофуразановой групп значительно снижает сродство лиганда к активному центру CYP7A1 и, в особенности, CYP7B1. Идентифицированы аминокислотные остатки, расположенные вблизи фотоактивируемых групп и способные образовывать с ними ковалентные аддукты. Полученные результаты представляют интерес для объяснения механизма взаимодействия соединений, содержащих фотоактивируемые сшивающие группы с рекомбинантными ферментами CYP7 человека in vitro, а также для идентификации продуктов ковалентной модификации аминокислотных остатков белка, образующихся при фотоактивации исследованных молекул

A homologue of the Parkinson's disease-associated protein LRRK2 undergoes a monomer-dimer transition during GTP turnover.

Mutations in LRRK2 are a common cause of genetic Parkinson's disease (PD). LRRK2 is a multi-domain Roco protein, harbouring kinase and GTPase activity. In analogy with a bacterial homologue, LRRK2 was proposed to act as a GTPase activated by dimerization (GAD), while recent reports suggest LRRK2 to exist under a monomeric and dimeric form in vivo. It is however unknown how LRRK2 oligomerization is regulated. Here, we show that oligomerization of a homologous bacterial Roco protein depends on the nucleotide load. The protein is mainly dimeric in the nucleotide-free and GDP-bound states, while it forms monomers upon GTP binding, leading to a monomer-dimer cycle during GTP hydrolysis. An analogue of a PD-associated mutation stabilizes the dimer and decreases the GTPase activity. This work thus provides insights into the conformational cycle of Roco proteins and suggests a link between oligomerization and disease-associated mutations in LRRK2

Insights into the Molecular Activation Mechanism of the RhoA-specific Guanine Nucleotide Exchange Factor, PDZRhoGEF

PDZRhoGEF (PRG) belongs to a small family of RhoA-specific nucleotide exchange factors that mediates signaling through select G-protein-coupled receptors via Gα(12/13) and activates RhoA by catalyzing the exchange of GDP to GTP. PRG is a multidomain protein composed of PDZ, regulators of G-protein signaling-like (RGSL), Dbl-homology (DH), and pleckstrin-homology (PH) domains. It is autoinhibited in cytosol and is believed to undergo a conformational rearrangement and translocation to the membrane for full activation, although the molecular details of the regulation mechanism are not clear. It has been shown recently that the main autoregulatory elements of PDZRhoGEF, the autoinhibitory "activation box" and the "GEF switch," which is required for full activation, are located directly upstream of the catalytic DH domain and its RhoA binding surface, emphasizing the functional role of the RGSL-DH linker. Here, using a combination of biophysical and biochemical methods, we show that the mechanism of PRG regulation is yet more complex and may involve an additional autoinhibitory element in the form of a molten globule region within the linker between RGSL and DH domains. We propose a novel, two-tier model of autoinhibition where the activation box and the molten globule region act synergistically to impair the ability of RhoA to bind to the catalytic DH-PH tandem. The molten globule region and the activation box become less ordered in the PRG-RhoA complex and dissociate from the RhoA-binding site, which may constitute a critical step leading to PRG activation