The survival protein SurE from Salmonella typhimurium (StSurE) is a dimeric protein that functions as a phosphatase. SurE dimers are formed by the swapping of a loop with a pair of β-strands and a C-terminal helix between two protomers. In a previous study, the Asp230 and His234 residues were mutated to Ala to abolish a hydrogen bond that was thought to be crucial for C-terminal helix swapping....

The recent solutions of the MHC class II crystal structure reveal dimerization of the alphabeta heterodimers. These dimer of dimers structures may also exist either on resting cells or after engagement by TCR, and may be involved in B cell signaling and up-regulation of co-stimulatory molecules such as B7 which facilitate T cell activation. By combining crystallographic data on HLA-DR1 with the...

Thermophilic organisms require proteins that maintain their structure and activity in the extreme temperature conditions in which their hosts thrive. In view of evaluating the influence of temperature on the different types of interactions that stabilize protein structures, we developed a new approach based on temperature-dependent mean force potentials. Our results show that the stabilizing we...

The formation of a salt bridge in deprotonated glycine dimer anions in a solvent-free environment is investigated using both infrared multiple photon dissociation spectroscopy between 600 and 1800 cm(-1) and theory. The zwitterionic and nonzwitterionic forms of glycine in this complex are computed to be nearly iso-energetic, yet predominantly the zwitterionic form is observed experimentally. Th...

The high-resolution structure of halophilic malate dehydrogenase (hMDH) from the archaebacterium Haloarcula marismortui was determined by x-ray crystallography. Comparison of the three-dimensional structures of hMDH and its nonhalophilic congeners reveals structural features that may promote the stability of hMDH at high salt concentrations. These features include an excess of acidic over basic...

Phosphorylation of the microtubule-associated protein Tau influences the assembly and stabilization of microtubules and is deregulated in several neurodegenerative diseases. The high flexibility of Tau, however, has prevented an atomic-level description of its phosphorylation-induced structural changes. Employing an extensive set of distance and orientational restraints together with a novel en...

0022-2836/$ see front matter © 2008 E The initial events in protein aggregation involve fluctuations that populate monomer conformations, which lead to oligomerization and fibril assembly. The highly populated structures, driven by a balance between hydrophobic and electrostatic interactions in the protease-resistant wild-type Aβ21–30 peptide and mutants E22Q (Dutch), D23N (Iowa), and K28N, are...

An experimental apparatus to study the breaking process of axisymmetric liquid bridges has been developed, and the breaking sequences of a large number of liquid bridge configurations at minimum-volume stability limit have been analyzed. Experimental results show that very close to the breaking moment the neck radius of the liquid bridge varies as t, where t is the time to breakage, irrespectiv...

The initial events in protein aggregation involve fluctuations that populate monomer conformations, which lead to oligomerization and fibril assembly. The highly populated structures, driven by a balance between hydrophobic and electrostatic interactions in the protease-resistant wild-type Abeta(21-30) peptide and mutants E22Q (Dutch), D23N (Iowa), and K28N, are analyzed using molecular dynamic...