Thermodynamics of aryl-dihydroxyphenyl-thiadiazole binding to human Hsp90.

The design of specific inhibitors against the Hsp90 chaperone and other enzyme relies on the detailed and correct understanding of both the thermodynamics of inhibitor binding and the structural features of the protein-inhibitor complex. Here we present a detailed thermodynamic study of binding of aryl-dihydroxyphenyl-thiadiazole inhibitor series to recombinant human Hsp90 alpha isozyme. The inhibitors are highly potent, with the intrinsic K(d) approximately equal to 1 nM as determined by isothermal titration calorimetry (ITC) and thermal shift assay (TSA).

Serendipitous discovery of novel bacterial methionine aminopeptidase inhibitors.

In this article we describe the application of structural biology methods to the discovery of novel potent inhibitors of methionine aminopeptidases. These enzymes are employed by the cells to cleave the N-terminal methionine from nascent peptides and proteins. As this is one of the critical steps in protein maturation, it is very likely that inhibitors of these enzymes may prove useful as novel antibacterial agents.

Forkhead transcription factor FOXO1A is critical for induction of human decidualization.

Experiments utilizing RNA interference technology were performed to determine whether the forkhead transcription factor FOXO1A, a member of the FOXO family of proteins, plays a critical role in the induction of human uterine decidualization. Human decidual fibroblast cells were decidualized in vitro for 6 days with medroxyprogester-one, estradiol, and dibutyryl cAMP in the presence or absence of a highly specific FOXO1A small interfering RNA (siRNA) that inhibits FOXO1A mRNA and protein expression by more than 80%. RNA and proteins were extracted from the cells at 0, 2, 4, and 6 days.

An evaluation of detergents for NMR structural studies of membrane proteins.

Structural information on membrane proteins lags far behind that on soluble proteins, in large part due to difficulties producing homogeneous, stable, structurally relevant samples in a membrane-like environment. In this study 25 membrane mimetics were screened using 2D (1)H-(15)N heteronuclear single quantum correlation NMR experiments to establish sample homogeneity and predict fitness for structure determination. A single detergent, 1-palmitoyl-2-hydroxy-sn-glycero-3-[phospho-RAC-(1-glycerol)] (LPPG), yielded high quality NMR spectra with sample lifetimes greater than one month for the five proteins tested - R.

Vancomycin tolerance induced by erythromycin but not by loss of vncRS, vex3, or pep27 function in Streptococcus pneumoniae.

Vancomycin-tolerant Streptococcus pneumoniae is a growing problem among drug-resistant human pathogens. Some vancomycin-tolerant pneumococci have been reported to carry mutations in loci encoding a two-component regulatory system designated VncRS or in a proximal ABC transporter, Vex. A model was advanced proposing that the tolerance phenotype resulted from the inability of a vncS mutant to respond to the Vex-transported Pep27 "death peptide" signal and dephosphorylate VncR, thereby preventing relief of repression of autolytic and other cell death functions in response to antibiotics.