RecA plays a central role in the nonmutagenic repair of stalled replication forks in bacteria. Rd... more RecA plays a central role in the nonmutagenic repair of stalled replication forks in bacteria. RdgC, a recombination-associated DNA-binding protein, is a potential negative regulator of RecA function. Here, we have determined the crystal structure of RdgC from Pseudomonas aeruginosa. The J-shaped monomer has a unique fold and can be divided into three structural domains: tip domain, center domain and base domain. Two such monomers dimerize to form a ring-shaped molecule of approximate 2-fold symmetry. Of the two inter-subunit interfaces within the dimer, one interface ('interface A') between tip/center domains is more nonpolar than the other ('interface B') between base domains. The structure allows us to propose that the RdgC dimer binds dsDNA through the central hole of $30 Å diameter. The proposed model is supported by our DNA-binding assays coupled with mutagenesis, which indicate that the conserved positively charged residues on the protein surface around the central hole play important roles in DNA binding. The novel ring-shaped architecture of the RdgC dimer has significant implications for its role in homologous recombination.
The work described in this report is about developing a framework for the design of concept of op... more The work described in this report is about developing a framework for the design of concept of operations (CONOP), which use small uninhabited aerial systems (SUAS) to support of intelligent transportation system (ITS) application of highway and transportation infrastructure monitoring. In these envisioned applications, these vehicles will be used for tasks such as remote collection of traffic data or inspection of roads and bridges. As such, a risk that has to be managed for these applications is that of vehicle-infrastructure collision. Various solutions to ensure safe separation between the unmanned aerial vehicle (UAV) and the object being inspected have been proposed. However, most, if not all, of these solutions rely on a multi-sensor approach, which combines digital maps of the infrastructure being inspected with an integrated GPS/Inertial navigator. While ``turn key" solutions for such multi-sensor systems exist, the performance specifications provided by their manufactures does not provide sufficient information to allow precisely quantifying or bounding the collision risk. Furthermore, size, weight and power (or SWAP) constraints posed by these small aerial vehicles limits the use of redundant hardware and/or software as a risk mitigation strategy. The purpose of the work reported here was to develop a framework for the design of CONOPs, which take these SUAS limitations into account. The method outlined shows, in part, how these vehicle/infrastructure collision risks can be estimated or conservatively bounded.
RecA plays a central role in the nonmutagenic repair of stalled replication forks in bacteria. Rd... more RecA plays a central role in the nonmutagenic repair of stalled replication forks in bacteria. RdgC, a recombination-associated DNA-binding protein, is a potential negative regulator of RecA function. Here, we have determined the crystal structure of RdgC from Pseudomonas aeruginosa. The J-shaped monomer has a unique fold and can be divided into three structural domains: tip domain, center domain and base domain. Two such monomers dimerize to form a ring-shaped molecule of approximate 2-fold symmetry. Of the two inter-subunit interfaces within the dimer, one interface ('interface A') between tip/center domains is more nonpolar than the other ('interface B') between base domains. The structure allows us to propose that the RdgC dimer binds dsDNA through the central hole of $30 Å diameter. The proposed model is supported by our DNA-binding assays coupled with mutagenesis, which indicate that the conserved positively charged residues on the protein surface around the central hole play important roles in DNA binding. The novel ring-shaped architecture of the RdgC dimer has significant implications for its role in homologous recombination.
The work described in this report is about developing a framework for the design of concept of op... more The work described in this report is about developing a framework for the design of concept of operations (CONOP), which use small uninhabited aerial systems (SUAS) to support of intelligent transportation system (ITS) application of highway and transportation infrastructure monitoring. In these envisioned applications, these vehicles will be used for tasks such as remote collection of traffic data or inspection of roads and bridges. As such, a risk that has to be managed for these applications is that of vehicle-infrastructure collision. Various solutions to ensure safe separation between the unmanned aerial vehicle (UAV) and the object being inspected have been proposed. However, most, if not all, of these solutions rely on a multi-sensor approach, which combines digital maps of the infrastructure being inspected with an integrated GPS/Inertial navigator. While ``turn key" solutions for such multi-sensor systems exist, the performance specifications provided by their manufactures does not provide sufficient information to allow precisely quantifying or bounding the collision risk. Furthermore, size, weight and power (or SWAP) constraints posed by these small aerial vehicles limits the use of redundant hardware and/or software as a risk mitigation strategy. The purpose of the work reported here was to develop a framework for the design of CONOPs, which take these SUAS limitations into account. The method outlined shows, in part, how these vehicle/infrastructure collision risks can be estimated or conservatively bounded.
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