The Pseudomonas aeruginosa AmrZ C-terminal domain mediates tetramerization and is required for its activator and repressor functions.

Pseudomonas aeruginosa is an important bacterial opportunistic pathogen, presenting a significant threat towards individuals with underlying diseases such as cystic fibrosis. The transcription factor AmrZ regulates expression of multiple P. aeruginosa virulence factors.

Effectively delivering a unique hsp90 inhibitor using star polymers.

We report the synthesis of a novel heat shock protein 90 (hsp90) inhibitor conjugated to a star polymer. Using reversible addition-fragmentation chain-transfer (RAFT) polymerization, we prepared star polymers comprised of PEG attached to a predesigned functional core. The stars were cross-linked using disulfide linkers, and a tagged version of our hsp90 inhibitor was conjugated to the polymer core to generate nanoparticles (14 nM).

Mechanistic studies of sanguinamide B derivatives: a unique inhibitor of eukaryotic ribosomes.

Described are mechanistic studies of two Sanguinamide B (San B) derivatives. These compounds were identified as eukaryotic ribosomal inhibitors. Two biotinylated San B derivatives were synthesized and used to capture protein targets in a pull-down assay.

Psammaplysin F: a unique inhibitor of bacterial chromosomal partitioning.

Described is the antibiotic activity of a marine natural product. Psammaplysin F (1) inhibited the growth of four Gram-positive strains by >80% at 50μM, and the amine at position C-20 is responsible for the observed antibacterial activity. When tested against two strains of methicillin resistant Staphylococcus aureus (MRSA), the minimum inhibitory concentrations (MICs) for psammaplysin F (40-80μM) were similar to the structurally-related alkaloid psammaplysin H (2).

A potential rhodium cancer therapy: studies of a cytotoxic organorhodium(I) complex that binds DNA.

Described is a novel organorhodium(I) complex that is cytotoxic to the colon cancer cell line HCT116 and alters cell migration, DNA replication, and DNA condensation. Most importantly, the mechanism observed is not seen for the parent organorhodium dimer complex [{RhCl(COD)}2], RhCl3, or the free ligand/proligands (COD and 1-(n)butyl-3-methylimidazolium chloride). Thus, the activity of this organorhodium complex is attributable to its unique structure.

A structure-activity relationship study on multi-heterocyclic molecules: two linked thiazoles are required for cytotoxic activity.

We report the synthesis, cytotoxicity, and phenotypic analysis of oxazole and thiazole containing fragments. Evaluating the optimal size and heterocycle for growth inhibition and apoptosis showed that activity required at least two thiazoles sequentially connected. This is the first detailed comparison of biological activity between multi-heterocyclic containing fragments.

Simultaneous bone marrow and composite tissue transplantation in rats treated with nonmyeloablative conditioning promotes tolerance.

Background: Approaches to safely induce tolerance in vascularized composite allotransplantation (VCA) with chimerism through bone marrow transplantation (BMT) are currently being pursued. However, VCA was historically performed sequentially after donor chimerism was established. Delayed VCA is not clinically applicable due to the time constraints associated with procurement from deceased donors.

Halting metastasis through CXCR4 inhibition.

Metastasis occurs when cancer cells leave the primary tumor site and migrate to distant parts of the body. The CXCR4-SDF-1 pathway facilitates this migration, and its expression has become the hallmark of several metastatic cancers. Targeted approaches are currently being developed to inhibit this pathway, and several candidates are now in clinical trials.

Synthesis, structure-activity analysis, and biological evaluation of sanguinamide B analogues.

We report the first synthesis of sanguinamide B analogues. Substituting N-methylated (N-Me) amino acids, glycine (Gly), and L- or D-phenylalanine (Phe) into the backbone of sanguinamide B showed that only l- and d-Phe residues controlled the macrocycle conformation. The N-methylated and glycine analogues all had multiple conformations, whereas the L- and D-Phe derivatives only had a single conformation.

An Hsp90 modulator that exhibits a unique mechanistic profile.

Described is the synthesis of two biotinylated derivatives of a cytotoxic macrocycle. Pull-down assays indicate that this macrocycle targets the N-middle domain of Hsp90. Untagged compound can effectively compete away tagged compound-Hsp90 protein complexes, confirming the binding specificity of the macrocycle for Hsp90.

Total synthesis of trans,trans-Sanguinamide B and conformational isomers.

The first total synthesis of Sanguinamide B is reported, prepared via an efficient synthetic strategy. The natural product, trans,trans-Sanguinamide B (1), was generated in a thermodynamic ratio with trans,cis-Sanguinamide B (2) and cis,cis-Sanguinamide B (3). Complete conversion of the cis,cis-Sanguinamide B conformer (3) to the natural product (1) and the trans,cis- conformer (2) was achieved by heating to 170 °C.

AmrZ beta-sheet residues are essential for DNA binding and transcriptional control of Pseudomonas aeruginosa virulence genes.

AmrZ is a putative ribbon-helix-helix (RHH) transcriptional regulator. RHH proteins utilize residues within the β-sheet for DNA binding, while the α-helices promote oligomerization. AmrZ is of interest due to its dual roles as a transcriptional activator and as a repressor, regulating genes encoding virulence factors associated with both chronic and acute Pseudomonas aeruginosa infection.

The Pseudomonas aeruginosa ribbon-helix-helix DNA-binding protein AlgZ (AmrZ) controls twitching motility and biogenesis of type IV pili.

Pseudomonas aeruginosa is an opportunistic pathogen that is commonly found in water and soil. In order to colonize surfaces with low water content, P. aeruginosa utilizes a flagellum-independent form of locomotion called twitching motility, which is dependent upon the extension and retraction of type IV pili.

Binding of Pseudomonas aeruginosa AlgZ to sites upstream of the algZ promoter leads to repression of transcription.

Mucoid variants of the opportunistic pathogen Pseudomonas aeruginosa produce the exopolysaccharide alginate and colonize the respiratory tracts of cystic fibrosis patients. The genes encoding the alginate biosynthetic enzymes are clustered in a single operon, which is under tight transcriptional control. One essential activator of the alginate operon is AlgZ, a proposed ribbon-helix-helix DNA binding protein that shares 30% amino acid identity with the Mnt repressor of Salmonella enterica serovar Typhimurium bacteriophage P22.

Understanding the control of Pseudomonas aeruginosa alginate synthesis and the prospects for management of chronic infections in cystic fibrosis.

Decades of research have been dedicated to the study of the opportunistic pathogen Pseudomonas aeruginosa, a Gram-negative, environmental bacterium that secretes the exopolysaccharide alginate during chronic lung infection of cystic fibrosis (CF) patients. Although P. aeruginosa utilizes a variety of factors to establish a successful infection in the lungs of CF patients, alginate has stood out as one of the best-studied prognostic indicators of chronic lung infection.