Common front end systems for Space Shuttle and Space Station control centers at Johnson Space Center

In the beginning of the fiscal year 1992, the development organizations of Johnson Space Center (JSC) were poised to begin two major projects: the Space Station Control Center and the refurbishment of the telemetry processing area of the Space Shuttle Mission Control Center. A study team established that a common front end concept could be used and could reduce development costs for both projects. A standard processor was defined to support most of the front end functions of both control centers and supports a consolidation of control positions which effectively reduces operations cost. This paper defines that common concept and describes the progress that has been made in development of the Consolidated Communications Facility (CCF) during the past year

Mechanistic consequences of temperature on DNA polymerization catalyzed by a Y-family DNA polymerase

Our previous publication shows that Sulfolobus solfataricus Dpo4 utilizes an ‘induced-fit’ mechanism to select correct incoming nucleotides at 37°C. Here, we provide a comprehensive report elucidating the kinetic mechanism of a DNA polymerase at a reaction temperature higher than 37°C in an attempt to determine the effect of temperature on enzyme fidelity and mechanism. The fidelity of Dpo4 did not change considerably with a 30°C increase in reaction temperature, suggesting that the fidelity of Dpo4 at 80°C is similar to that determined here at 56°C. Amazingly, the incorporation rate for correct nucleotides increased by 18 900-fold from 2°C to 56°C, similar in magnitude to that observed for incorrect nucleotides, thus not perturbing fidelity. Three independent lines of kinetic evidence indicate that a protein conformational change limits correct nucleotide incorporations at 56°C. Furthermore, the activation energy for the incorporation of a correct nucleotide was determined to be 32.9 kcal/mol, a value considerably larger than those values estimated for a rate-limiting chemistry step, providing a fourth line of evidence to further substantiate this conclusion. These results herein provide evidence that Dpo4 utilizes the ‘induced-fit’ mechanism to select a correct nucleotide at all temperatures

Structure of Human DNA Polymerase κ Inserting dATP Opposite an 8-OxoG DNA Lesion

Background: Oxygen-free radicals formed during normal aerobic cellular metabolism attack bases in DNA and 7,8-dihydro-8-oxoguanine (8-oxoG) is one of the major lesions formed. It is amongst the most mutagenic lesions in cells because of its dual coding potential, wherein 8-oxoG(syn) can pair with an A in addition to normal base pairing of 8-oxoG(anti) with a C. Human DNA polymerase κ (Polκ) is a member of the newly discovered Y-family of DNA polymerases that possess the ability to replicate through DNA lesions. To understand the basis of Polκ\u27s preference for insertion of an A opposite 8-oxoG lesion, we have solved the structure of Polκ in ternary complex with a template-primer presenting 8-oxoG in the active site and with dATP as the incoming nucleotide. Methodology and Principal Findings: We show that the Polκ active site is well-adapted to accommodate 8-oxoG in the syn conformation. That is, the polymerase and the bound template-primer are almost identical in their conformations to that in the ternary complex with undamaged DNA. There is no steric hindrance to accommodating 8-oxoG in the syn conformation for Hoogsteen base-paring with incoming dATP. Conclusions and Significance: The structure we present here is the first for a eukaryotic translesion synthesis (TLS) DNA polymerase with an 8-oxoG:A base pair in the active site. The structure shows why Polκ is more efficient at inserting an A opposite the 8-oxoG lesion than a C. The structure also provides a basis for why Polκ is more efficient at inserting an A opposite the lesion than other Y-family DNA polymerases

Mutations at the Subunit Interface of Yeast Proliferating Cell Nuclear Antigen Reveal a Versatile Regulatory Domain

Acknowledgments We thank Szilvia Minorits for technical assistance. I.U. conceived and designed the project and wrote the manuscript. All authors participated in designing and performing the experiments, and analyzing the results. The authors declare no competing financial interests. This work was also supported by a grant from the National Research, Development and Innovation Office GINOP-2.3.2-15-2016-00001. Funding: This work was supported by Hungarian Science Foundation Grant OTKA 109521 and National Research Development and Innovation Office GINOP-2.3.2-15-2016-00001. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

A nucleotide binding rectification Brownian ratchet model for translocation of Y-family DNA polymerases

Y-family DNA polymerases are characterized by low-fidelity synthesis on undamaged DNA and ability to catalyze translesion synthesis over the damaged DNA. Their translocation along the DNA template is an important event during processive DNA synthesis. In this work we present a Brownian ratchet model for this translocation, where the directed translocation is rectified by the nucleotide binding to the polymerase. Using the model, different features of the available structures for Dpo4, Dbh and polymerase ι in binary and ternary forms can be easily explained. Other dynamic properties of the Y-family polymerases such as the fast translocation event upon dNTP binding for Dpo4 and the considerable variations of the processivity among the polymerases can also be well explained by using the model. In addition, some predicted results of the DNA synthesis rate versus the external force acting on Dpo4 and Dbh polymerases are presented. Moreover, we compare the effect of the external force on the DNA synthesis rate of the Y-family polymerase with that of the replicative DNA polymerase

Generic Telemetry Processing in the Control Center Environment at Johnson Space Center

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, NevadaThis paper will describe the effort to provide a common telemetry system for the Control Center Complex (CCC) which will process data from both the space shuttle and the space station vehicles. It is being developed for the manned spaceflight program at Johnson Space Center. Space shuttle uses a traditional Inter-Range Instrumentation Group (IRIG) telemetry format and Space Station Freedom utilizes the more recently developed Consultative Committee for Space Data Systems (CCSDS) standards for packet-based telemetry Although the two telemetry streams are very different in structure, a front end system is being developed which will isolate the differences and provide a common data format to the downstream elements of the control center. Because of this, a CCC workstation could receive and process data from either space station or space shuttle or both using a identical set of workstation program tools. The generic telemetry front end processor, which is called the Consolidated Communications Facility (CCF), will not only provide a cost effective method of processing space shuttle and space station data, but also will position the CCC to support anticipated requirements of' future programs. The development goals for the CCC are to reduce development and sustaining costs. In the CCF project, commercial-off-the-shelf (COTS) equipment is stressed to allow modular maintenance. In addition, the project has emphasized the development of a automated features in the telemetry stream selection and processing which reduce the amount of operator attention needed. The system has been designed to include robotics in the recording operation and artificial intelligence for detecting faults. This paper will review the concept development for processing telemetry and outline the architecture of the front end CCF project. It will discuss the goals and major influences on the design, and provide a status on the development. Ability of the current COTS marketplace to meet the goals will be discussed. In summation, this paper will describe generic telemetry processing in the context of the CCC being built at Johnson Space Center.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Initial and Continued Knowledge Contribution on Enterprise Social Media Platforms

In recent years, social media has entered enterprises as a tool for internal communication, collaboration, and knowledge management. However, it has been reported that knowledge contribution rates are low which raises questions on the reasons for it and how to improve the situation. To address these questions, we take a deep look into the individual knowledge contribution process using an integrative model that explains the initial formation of the intention to contribute knowledge and the continued knowledge contribution. Towards this goal, we apply the theory of reasoned action, the social exchange theory, and the belief-adjustment model. In this research in progress, we present our research model and a test covering the first part of the model, the formation of the intention to contribute knowledge. The results suggest that social exchange theory and theory of reasoned action are well suited to explain this phenomenon and that they build a good basis for the second part of the longitudinal study