Combining Metabolite-Based Pharmacophores with Bayesian Machine Learning Models for Mycobacterium tuberculosis Drug Discovery.

Integrated computational approaches for Mycobacterium tuberculosis (Mtb) are useful to identify new molecules that could lead to future tuberculosis (TB) drugs. Our approach uses information derived from the TBCyc pathway and genome database, the Collaborative Drug Discovery TB database combined with 3D pharmacophores and dual event Bayesian models of whole-cell activity and lack of cytotoxicity. We have prioritized a large number of molecules that may act as mimics of substrates and metabolites in the TB metabolome.

Machine Learning Models and Pathway Genome Data Base for Trypanosoma cruzi Drug Discovery.

Background: Chagas disease is a neglected tropical disease (NTD) caused by the eukaryotic parasite Trypanosoma cruzi. The current clinical and preclinical pipeline for T. cruzi is extremely sparse and lacks drug target diversity.

In situ data collection and structure refinement from microcapillary protein crystallization.

In situ X-ray data collection has the potential to eliminate the challenging task of mounting and cryocooling often fragile protein crystals, reducing a major bottleneck in the structure determination process. An apparatus used to grow protein crystals in capillaries and to compare the background X-ray scattering of the components, including thin-walled glass capillaries against Teflon, and various fluorocarbon oils against each other, is described. Using thaumatin as a test case at 1.

Crystal structure of nonstructural protein 10 from the severe acute respiratory syndrome coronavirus reveals a novel fold with two zinc-binding motifs.

The severe acute respiratory syndrome coronavirus (SARS-CoV) possesses a large 29.7-kb positive-stranded RNA genome. The first open reading frame encodes replicase polyproteins 1a and 1ab, which are cleaved to generate 16 "nonstructural" proteins, nsp1 to nsp16, involved in viral replication and/or RNA processing.

Coiled coils at the edge of configurational heterogeneity. Structural analyses of parallel and antiparallel homotetrameric coiled coils reveal configurational sensitivity to a single solvent-exposed amino acid substitution.

A detailed understanding of the mechanisms by which particular amino acid sequences can give rise to more than one folded structure, such as for proteins that undergo large conformational changes or misfolding, is a long-standing objective of protein chemistry. Here, we describe the crystal structures of a single coiled-coil peptide in distinct parallel and antiparallel tetrameric configurations and further describe the parallel or antiparallel crystal structures of several related peptide sequences; the antiparallel tetrameric assemblies represent the first crystal structures of GCN4-derived peptides exhibiting such a configuration. Intriguingly, substitution of a single solvent-exposed residue enabled the parallel coiled-coil tetramer GCN4-pLI to populate the antiparallel configuration, suggesting that the two configurations are close enough in energy for subtle sequence changes to have important structural consequences.

Structure-based engineering of internal cavities in coiled-coil peptides.

Cavities and clefts are frequently important sites of interaction between natural enzymes or receptors and their corresponding substrate or ligand molecules and exemplify the types of molecular surfaces that would facilitate engineering of artificial catalysts and receptors. Even so, structural characterizations of designed cavities are rare. To address this issue, we performed a systematic study of the structural effects of single-amino acid substitutions within the hydrophobic cores of tetrameric coiled-coil peptides.

Heterocyclic peptide backbone modifications in an alpha-helical coiled coil.

In this paper, we present 1,2,3-triazole epsilon2-amino acids incorporated as a dipeptide surrogate at three positions in the sequence of a known alpha-helical coiled coil. Biophysical characterization indicates that the modified peptides retain much of the helical structure of the parent sequence, and that the thermodynamic stability of the coiled coil depends on the position of the incorporation of the epsilon-residue. Crystal structures obtained for each peptide give insight into the chemical behavior and conformational preferences of the non-natural amino acid and show that the triazole ring can participate in the backbone hydrogen bonding of the alpha-helix as well as template an interhelical crossing between chains in the bundle.

Design of a directed molecular network.

An ability to rationally design complex networks from the bottom up can offer valuable quantitative model systems for use in gaining a deeper appreciation for the principles governing the self-organization and functional characteristics of complex systems. We report herein the de novo design, graph prediction, experimental analysis, and characterization of simple self-organized, nonlinear molecular networks. Our approach makes use of the sequence-dependent auto- and cross-catalytic functional characteristics of template-directed peptide fragment condensation reactions in neutral aqueous solutions.