Foreword

Proteins that contain long disordered regions are prevalent in the proteome and frequently associated with diseases. However, the mechanisms by which such intrinsically disordered proteins (IDPs) recognize their targets are not well understood. Here, we report the first experimental investigation of the interaction kinetics of the nuclear co-activator binding domain of CREB-binding protein and the activation domain from the p160 transcriptional co-activator for thyroid hormone and retinoid receptors. Both protein domains are intrinsically disordered in the free state and synergistically fold upon binding each other. Using the stopped-flow technique, we found that the binding reaction is fast, with an association rate constant of 3 x 10(7) M-1 s(-1) at 277 K. Mutation of a conserved buried intermolecular salt bridge showed that electrostatics govern the rapid association. Furthermore, upon mutation of the salt bridge or at high salt concentration, an additional kinetic phase was detected (similar to 20 and similar to 40 s(-1), respectively, at 277 K), suggesting that the salt bridge may steer formation of the productive bimolecular complex in an intramolecular step. Finally, we directly measured slow kinetics for the IDP domains (similar to 1 s(-1) at 277 K) related to conformational transitions upon binding. Together, the experiments demonstrate that the interaction involves several steps and accumulation of intermediate states. Our data are consistent with an induced fit mechanism, in agreement with previous simulations. We propose that the slow transitions may be a consequence of the multipartner interactions of IDPs

Chronic development of collagen-induced arthritis is associated with arthritogenic antibodies against specific epitopes on type II collagen

Antibodies against type II collagen (CII) are important in the development of collagen-induced arthritis (CIA) and possibly also in rheumatoid arthritis. We have determined the fine specificity and arthritogenicity of the antibody response to CII in chronic relapsing variants of CIA. Immunization with rat CII in B10.Q or B10.Q(BALB/c×B10.Q)F(2 )mice induces a chronic relapsing CIA. The antibody response to CII was determined by using triple-helical peptides of the major B cell epitopes. Each individual mouse had a unique epitope-specific response and this epitope predominance shifted distinctly during the course of the disease. In the B10.Q mice the antibodies specific for C1 and U1, and in the B10.Q(BALB/c×B10.Q)F(2 )mice the antibodies specific for C1, U1 and J1, correlated with the development of chronic arthritis. Injection of monoclonal antibodies against these epitopes induced relapses in chronic arthritic mice. The development of chronic relapsing arthritis, initially induced by CII immunization, is associated with an arthritogenic antibody response to certain CII epitopes

Structure and pathogenicity of antibodies specific for citrullinated collagen type II in experimental arthritis

Antibodies to citrulline-modifi ed proteins have a high diagnostic value in rheumatoid arthritis (RA). However, their biological role in disease development is still unclear. To obtain insight into this question, a panel of mouse monoclonal antibodies was generated against a major triple helical collagen type II (CII) epitope (position 359 – 369; ARGLTGRPGDA) with or without arginines modifi ed by citrullination. These antibodies bind cartilage and synovial tissue, and mediate arthritis in mice. Detection of citrullinated CII from RA patients ’ synovial fl uid demonstrates that cartilage-derived CII is indeed citrullinated in vivo. The structure determination of a Fab fragment of one of these antibodies in complex with a citrullinated peptide showed a surprising beta -turn conformation of the peptide and provided information on citrulline recognition. Based on these findings, we propose that autoimmunity to CII, leading to the production of antibodies specific for both native and citrullinated CII, is an important pathogenic factor in the development of RA

Редокс-регуляция динамического характера фенотипа эндотелиоцитов кровеносных сосудов

ЭНДОТЕЛИАЛЬНЫЕ КЛЕТКИКЛЕТКИЭНДОТЕЛИЙКРОВЕНОСНЫЕ СОСУДЫФЕНОТИПГЕНЕТИЧЕСКИЕ ФЕНОМЕНЫОКИСЛИТЕЛЬНО-ВОССТАНОВИТЕЛЬНЫЕ РЕАКЦИИЭНЕРГЕТИЧЕСКИЙ ОБМЕНПЕРЕКИСНОЕ ОКИСЛЕНИЕ ЛИПИДО

N-glycans of Human Protein C Inhibitor: Tissue-Specific Expression and Function

Protein C inhibitor (PCI) is a serpin type of serine protease inhibitor that is found in many tissues and fluids in human, including blood plasma, seminal plasma and urine. This inhibitor displays an unusually broad protease specificity compared with other serpins. Previous studies have shown that the N-glycan(s) and the NH2-terminus affect some blood-related functions of PCI. In this study, we have for the first time determined the N-glycan profile of seminal plasma PCI, by mass spectrometry. The N-glycan structures differed markedly compared with those of both blood-derived and urinary PCI, providing evidence that the N-glycans of PCI are expressed in a tissue-specific manner. The most abundant structure (m/z 2592.9) had a composition of Fuc3Hex5HexNAc4, consistent with a core fucosylated bi-antennary glycan with terminal Lewisx. A major serine protease in semen, prostate specific antigen (PSA), was used to evaluate the effects of N-glycans and the NH2-terminus on a PCI function related to the reproductive tract. Second-order rate constants for PSA inhibition by PCI were 4.3±0.2 and 4.1±0.5 M−1s−1 for the natural full-length PCI and a form lacking six amino acids at the NH2-terminus, respectively, whereas these constants were 4.8±0.1 and 29±7 M−1s−1 for the corresponding PNGase F-treated forms. The 7–8-fold higher rate constants obtained when both the N-glycans and the NH2-terminus had been removed suggest that these structures jointly affect the rate of PSA inhibition, presumably by together hindering conformational changes of PCI required to bind to the catalytic pocket of PSA

Two Cellular Protein Kinases, DNA-PK and PKA, Phosphorylate the Adenoviral L4-33K Protein and Have Opposite Effects on L1 Alternative RNA Splicing

Accumulation of the complex set of alternatively processed mRNA from the adenovirus major late transcription unit (MLTU) is subjected to a temporal regulation involving both changes in poly (A) site choice and alternative 3′ splice site usage. We have previously shown that the adenovirus L4-33K protein functions as an alternative splicing factor involved in activating the shift from L1-52,55K to L1-IIIa mRNA. Here we show that L4-33K specifically associates with the catalytic subunit of the DNA-dependent protein kinase (DNA-PK) in uninfected and adenovirus-infected nuclear extracts. Further, we show that L4-33K is highly phosphorylated by DNA-PK in vitro in a double stranded DNA-independent manner. Importantly, DNA-PK deficient cells show an enhanced production of the L1-IIIa mRNA suggesting an inhibitory role of DNA-PK on the temporal switch in L1 alternative RNA splicing. Moreover, we show that L4-33K also is phosphorylated by protein kinase A (PKA), and that PKA has an enhancer effect on L4-33K-stimulated L1-IIIa splicing. Hence, we demonstrate that these kinases have opposite effects on L4-33K function; DNA-PK as an inhibitor and PKA as an activator of L1-IIIa mRNA splicing. Taken together, this is the first report identifying protein kinases that phosphorylate L4-33K and to suggest novel regulatory roles for DNA-PK and PKA in adenovirus alternative RNA splicing

Opportunities for Improving Virtual Team Performance.

Globālās tendences parāda, ka, ņemot vērā globalizācijas ietekmi, kā arī informācijas un komunikācijas tehnoloģiju attīstību un pieejamību, aizvien pieaug virtuālā darba popularitāte. Organizācijas aktīvi apgūst virtuālā darba priekšrocības, lai neatkarīgi no ģeogrāfiskās atrašanās vietas neierobežoti piesaistītu talantīgu darbaspēku, samazinātu izmaksas un paplašinātu savu darbību globālajā tirgū. Tomēr, veidojot virtuālas komandas, kuru savstarpējā sadarbība balstās komunikācijā ar datora starpniecību, ir būtiski novērtēt virtualitātes ietekmi uz komandas sniegumu. Šī pētījuma mērķis ir, pamatojoties uz zinātniskās literatūras analīzi, kā arī šī pētījuma ietvaros veiktā eksperimenta un aptaujas rezultātiem, novērtēt uzdevumu savstarpējās atkarības un virtualitātes pakāpes ietekmi uz komandas darba rezultātiem. Eksperimentā piedalījās 40 trīs cilvēku komandas, kuras iedalījās četru dažādu nosacījumu komandās ar atšķirīgām virtualitātes un savstarpējās atkarības pakāpēm. Pētījuma rezultāti statistiski nozīmīgi apstiprināja, ka tradicionālajām komandām vidēji ir labāki darba rezultāti nekā virtuālajām komandām, bet komandas ar zemu savstarpēju atkarību uzdevumu paveic vidēji ātrāk un kvalitatīvāk, savukārt starp virtuālo un tradicionālo komandu dalībniekiem neatšķīrās vērtējumi par apgalvojumiem, kas saistīti ar komandas darbam nepieciešamo zināšanu, prasmju un spēju, nozīmīgumu, t.i., gan virtuālo, gan tradicionālo komandu dalībnieki atzina, ka komandas dalībnieku komunikācijas un sadarbošanās zināšanas, prasmes un spējas ir svarīgas neatkarīgi no komandas virtualitātes pakāpes. Pētījuma rezultātā iegūtie secinājumi papildina pētniecisko bāzi par virtuālo komandu sniegumu, savukārt autoru izstrādātos priekšlikumus organizāciju līderi un personālvadības profesionāļi var lietot efektīvākai darba organizācijai uzņēmumos.Taking into consideration the impact of globalization, as well as the development and accessibility of information and communication technologies, worldwide tendencies indicate that popularity of virtual teams is ever-growing. Making a good use of virtual team advantages, companies are able to more successfully attract skilled and talented workforce, decrease expenses, and expand their operations in the global market, no matter where are workers working from. However, forming teams of virtual workers, whose mutual cooperation depends on computer-mediated communication, it is crucial to estimate the impact of virtual environment on team’s performance. Based on the analysis of scientific literature, as well as the findings of the experiment and the survey that were carried out within this particular research, the research aim is as follows: to evaluate the impact of task interdependence and level of virtuality on team's performance. Altogether, 40 teams, consisting of 3 members, participated in the experiment. The teams were divided into 4 groups, depending on different variables in terms of virtuality and task interdependence. The most significant finding was the one that confirmed efficiency of traditional teams – on average, they had better work results than virtual teams. On average, teams with lower interdependence are able to carry out task quicker and of better quality. Conversely, among virtual and traditional teams’ evaluations on assertions that are connected to knowledge, skills, and abilities required for working in team, opinions were similar – both traditional and virtual teams agreed that team members’ knowledge of communication and cooperation are important, regardless of level of virtuality. Conclusions that are drawn in the research are a great addition to resources on efficiency of virtual teams, whereas the authors’ developed proposals can be used by leaders and HR specialists in the companies, in order to maintain efficient work organization within the companies