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Biomedical subjects

Anne Roberts

Publications and source records attributed to Anne Roberts.

6 recordsLinked to original sources
PubMed2006

Structural studies of MJ1529, an O6-methylguanine-DNA methyltransferase.

The structure of an O6-methylguanine-DNA methyltransferase (MGMT) from the thermophile Methanococcus jannaschii has been determined using multinuclear multidimensional NMR spectroscopy. The structure is similar to homologs from other organisms that have been determined by crystallography, with some variation in the N-terminal domain. The C-terminal domain is more highly conserved in both sequence and structure. Regions of the protein show broadening, reflecting conformational flexibility that is likely related to function.

Amino Acid Sequence↗
PubMed2005

YbiV from Escherichia coli K12 is a HAD phosphatase.

The protein YbiV from Escherichia coli K12 MG1655 is a hypothetical protein with sequence homology to the haloacid dehalogenase (HAD) superfamily of proteins. Although numerous members of this family have been identified, the functions of few are known. Using the crystal structure, sequence analysis, and biochemical assays, we have characterized YbiV as a HAD phosphatase. The crystal structure of YbiV reveals a two-domain protein, one with the characteristic HAD hydrolase fold, the other an inserted alpha/beta fold. In an effort to understand the mechanism, we also solved and report the structures of YbiV in complex with beryllofluoride (BeF3-) and aluminum trifluoride (AlF3), which have been shown to mimic the phosphorylated intermediate and transition state for hydrolysis, respectively, in analogy to other HAD phosphatases. Analysis of the structures reveals the substrate-binding cavity, which is hydrophilic in nature. Both structure and sequence homology indicate YbiV may be a sugar phosphatase, which is supported by biochemical assays that measured the release of free phosphate on a number of sugar-like substrates. We also investigated available genomic and functional data in an effort to determine the physiological substrate.

Adenosine Monophosphate↗
PubMed2005

Adding quetiapine to SRI in treatment-resistant obsessive-compulsive disorder: a randomized controlled treatment study.

This study aimed to determine the efficacy and tolerability of adding quetiapine to a serotonin reuptake inhibitor in treatment-resistant obsessive-compulsive disorder (OCD). Twenty-one adult treatment-resistant OCD patients were randomized to 16 weeks of augmentation with either quetiapine (n = 11) or placebo (n = 10). Patients with significant comorbidities, including tic-spectrum disorders, were not included. The treatment was well tolerated, with only one premature dropout in each treatment-group. The primary analysis showed that individuals in the quetiapine-treated group showed a 14% mean improvement in baseline Yale-Brown Obsessive-Compulsive Scale scores at study endpoint compared with a 6% improvement in those treated with placebo, but this difference did not reach statistical significance (F<1). Three patients treated with quetiapine met criteria for clinical response, compared to one patient who was treated with placebo. Larger studies are needed to explore the efficacy of second generation antipsychotics, such as quetiapine, when used as adjunct treatment in resistant OCD.

Adult↗
PubMed2003

Crystal structure of a phosphatase with a unique substrate binding domain from Thermotoga maritima.

We have determined the crystal structure of a phosphatase with a unique substrate binding domain from Thermotoga maritima, TM0651 (gi 4981173), at 2.2 A resolution by selenomethionine single-wavelength anomalous diffraction (SAD) techniques. TM0651 is a member of the haloacid dehalogenase (HAD) superfamily, with sequence homology to trehalose-6-phosphate phosphatase and sucrose-6(F)-phosphate phosphohydrolase. Selenomethionine labeled TM0651 crystallized in space group C2 with three monomers per asymmetric unit. Each monomer has approximate dimensions of 65 x 40 x 35 A(3), and contains two domains: a domain of known hydrolase fold characteristic of the HAD family, and a domain with a new tertiary fold consisting of a six-stranded beta-sheet surrounded by four alpha-helices. There is one disulfide bond between residues Cys35 and Cys265 in each monomer. One magnesium ion and one sulfate ion are bound in the active site. The superposition of active site residues with other HAD family members indicates that TM0651 is very likely a phosphatase that acts through the formation of a phosphoaspartate intermediate, which is supported by both NMR titration data and a biochemical assay. Structural and functional database searches and the presence of many aromatic residues in the interface of the two domains suggest the substrate of TM0651 is a carbohydrate molecule. From the crystal structure and NMR data, the protein likely undergoes a conformational change upon substrate binding.

Acid Phosphatase↗