Solution structure of an arsenate reductase-related protein, YffB, from Brucella melitensis, the etiological agent responsible for brucellosis

B. melitensis is a NIAID Category B microorganism that is responsible for brucellosis and is a potential agent for biological warfare. Here, the solution structure of the 116-residue arsenate reductase-related protein Bm-YffB (BR0369) from this organism is reported

Structure of a Nudix hydrolase (MutT) in the Mg2+-­bound state from Bartonella henselae, the bacterium responsible for cat scratch fever

B. henselae is the etiological agent responsible for cat scratch fever (bartonellosis). The crystal structure of the smaller of the two Nudix hydrolases encoded in the genome of B. henselae, Bh-MutT, was determined to 2.1 Å resolution

Solution Structure of the Conserved Hypothetical Protein Rv2302 from Mycobacterium tuberculosis

The Mycobacterium tuberculosis protein Rv2302 (80 residues; molecular mass of 8.6 kDa) has been characterized using nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. While the biochemical function of Rv2302 is still unknown, recent microarray analyses show that Rv2302 is upregulated in response to starvation and overexpression of heat shock proteins and, consequently, may play a role in the biochemical processes associated with these events. Rv2302 is a monomer in solution as shown by size exclusion chromatography and NMR spectroscopy. CD spectroscopy suggests that Rv2302 partially unfolds upon heating and that this unfolding is reversible. Using NMR-based methods, the solution structure of Rv2302 was determined. The protein contains a five-strand, antiparallel β-sheet core with one C-terminal α-helix (A61 to A75) nestled against its side. Hydrophobic interactions between residues in the α-helix and β-strands 3 and 4 hold the α-helix near the β-sheet core. The electrostatic potential on the solvent-accessible surface is primarily negative with the exception of a positive arginine pocket composed of residues R18, R70, and R74. Steady-state {(1)H}-(15)N heteronuclear nuclear Overhauser effects indicate that the protein's core is rigid on the picosecond timescale. The absence of amide cross-peaks for residues G13 to H19 in the (1)H-(15)N heteronuclear single quantum correlation spectrum suggests that this region, a loop between β-strands 1 and 2, undergoes motion on the millisecond to microsecond timescale. Dali searches using the structure closest to the average structure do not identify any high similarities to any other known protein structure, suggesting that the structure of Rv2302 may represent a novel protein fold

Functional and Structural Characterization of DR_0079 fromDeinococcus radiodurans, a Novel Nudix Hydrolase with a Preference for Cytosine (Deoxy)ribonucleoside 5′-Di- and Triphosphates†

Photograph of a scene during the Jazz and Blues Festival

Evaluating the role of acidic, basic, and polar amino acids and dipeptides on a molecular electrocatalyst for H2oxidation

Amino acids and peptides have been shown to have a significant influence on the H2 production and oxidation reactivity of Ni(PR2NR′2)2, where PR2NR′2 = 1,5-diaza-3,7-diphosphacyclooctane, R is either phenyl (Ph) or cyclohexyl (Cy), and R′ is either an amino acid or peptide. Most recently, the Ni(PCy2Naminoacid2)2 complexes (CyAA) have shown enhanced H2 oxidation rates, water solubility, and in the case of arginine (CyArg) and phenylalanine (CyPhe), electrocatalytic reversibility. Both the backbone –COOH and side chain interactions were shown to be critical to catalytic performance. Here we further investigate the roles of the outer coordination sphere by evaluating amino acids with acidic, basic, and hydrophilic side chains, as well as dipeptides which combine multiple successful features from previous complexes. Six new complexes were prepared, three containing single amino acids: aspartic acid (CyAsp), lysine (CyLys), and serine (CySer) and three containing dipeptides: glycine-phenylalanine (Cy(GlyPhe)), phenylalanine-glycine (Cy(PheGly)), and aspartic acid-phenylananine (Cy(AspPhe)). The resulting catalytic performance demonstrates that complexes need both interactions between side chain and –COOH groups for fast, efficient catalysis. The fastest of all of the catalysts, Cy(AspPhe), had both of these features, while the other dipeptide complexes with an amide replacing the –COOH were both slower; however, the amide group was demonstrated to participate in the proton pathway when side chain interactions are present to position it. Both the hydrophilic and basic side chains, notably lacking in side chain interactions, significantly increased the overpotential, with only modest increases in TOF. Of all of the complexes, only CyAsp was electrocatalytically reversible at room temperature, and only in water, the first of these complexes to demonstrate room temperature aqueous electrocatalytic reversibility for the H2/H+ transformation. These results continue to provide and solidify design rules for controlling reactivity and efficiency of Ni(P2N2)2 complexes with the outer coordination sphere.by Nilusha Priyadarshani Boralugodage, Rajith Jayasingha Arachchige, Arnab Dutta, Garry W. Buchko and Wendy J. Sha

High-level expression, purification, crystallization and preliminary X-ray crystallographic studies of the receptor-binding domain of botulinum neurotoxin serotype D

The receptor-binding domain of botulinum neurotoxin serotype D was expressed in E. coli using a codon-optimized cDNA. The highly purified protein crystallized in space group P212121, with unit-cell parameters a = 60.8, b = 89.7, c = 93.9 Å, and the crystals diffracted to 1.65 Å resolution