FeeM, an N-acyl amino acid synthase from an uncultured soil microbe: structure, mechanism, and acyl carrier protein binding.

Attempts to access antibiotics by capturing biosynthetic genes and pathways directly from environmental DNA, which is overwhelmingly derived from uncultured bacteria, have revealed a large and previously unknown family of N-acyl amino acid synthases (NASs). The structure of the NAS FeeM reveals structural similarity to the GCN5-related N-acyl transferases and acylhomoserine lactone synthases. The overall structure has a central beta sheet with alpha helices on both sides.

Preparation of a psammaplysene-based library.

A 28-member focused library, based on the pseudosymmetric template of the marine alkaloids psammaplysenes, was prepared from combinations of components that were, in turn, derived from 4-iodophenol.

Phaeosphaeride A, an inhibitor of STAT3-dependent signaling isolated from an endophytic fungus.

Phaeosphaeride A, a nitrogen-containing bicyclic compound produced by an endophytic fungus, inhibits signaling by the transcription factor STAT3.

A biosynthetic gene cluster for the acetyl-CoA carboxylase inhibitor andrimid.

Increasing bacterial resistance to antibiotics with conventional targets has focused attention on antibiotics with unconventional targets. One promising candidate, the acetyl-CoA carboxylase (ACC) inhibitor andrimid, is a potent, broad-spectrum antibiotic with high selectivity for prokaryotic ACC. Here, we report the use of a DNA-based approach to clone the andrimid biosynthetic gene cluster from Pantoea agglomerans, yielding a cosmid that confers robust andrimid production on Escherichia coli.

Bisandrographolide from Andrographis paniculata activates TRPV4 channels.

Many transient receptor potential (TRP) channels are activated or blocked by various compounds found in plants; two prominent examples include the activation of TRPV1 channels by capsaicin and the activation of TRPM8 channels by menthol. We sought to identify additional plant compounds that are active on other types of TRP channels. We screened a library of extracts from 50 Chinese herbal plants using a calcium-imaging assay to find compounds active on TRPV3 and TRPV4 channels.

Isolation and structure assignment of an iminotetrasaccharide from a cultured filamentous cyanobacterium Anabaena sp.

In search of bioactive metabolites in cultured microalgae, a novel acylated iminopseudotetrasaccharide was isolated from a filamentous cyanobacterium Anabaena sp., and its structure was established by NMR, chemical degradation, and X-ray crystallography. The compound consists of glucose, glucuronic acid, arabinose, and 1,4,6-trideoxy-1,4-imino-D-allitol, which is closely related to potent glucosidase inhibitors such as nojirimycin.

Human methionine aminopeptidase type 2 in complex with L- and D-methionine.

Human methionine aminopeptidase type 2 (hMetAP-2) was identified as the molecular target of anti-angiogenic agents such as fumagillin and its analogues. We describe here the crystal structure of hMetAP-2 in complex with l-methionine and d-methionine at 1.9 and 2.

Structure of Plasmodium falciparum dihydroorotate dehydrogenase with a bound inhibitor.

Membrane-associated dihydroorotate dehydrogenase (DHODH) is an antimalarial therapeutic target without an effective inhibitor. Studies on human DHODH (HsDHODH) led to a structural mechanistic model in which respiratory quinones bind in a tunnel formed by the highly variable N-terminus that leads to the flavin mononucleotide-binding site. The therapeutic agents leflunomide (Arava) and brequinar sodium inhibit HsDHODH by binding in this tunnel.

Brequinar derivatives and species-specific drug design for dihydroorotate dehydrogenase.

Therapeutic agents brequinar sodium and leflunomide (Arava) work by binding in a hydrophobic tunnel formed by a highly variable N-terminus of family 2 dihydroorotate dehydrogenase (DHODH). The X-ray crystallographic structure of an analog of brequinar bound to human DHODH was determined. In silico screening of a library of compounds suggested another subset of brequinar analogs that do not inhibit human DHODH as potentially effective inhibitors of Plasmodium falciparum DHODH.

Using genomics to deliver natural products from symbiotic bacteria.

The availability of some natural products with promising anticancer activity has been limited because they are synthesized by symbiotic bacteria associated with specific animals. Recent research has identified the clusters of bacterial genes responsible for their synthesis, so that the molecules can be synthesized in alternative, easily cultured bacteria.

Total synthesis of psammaplysenes A and B, naturally occurring inhibitors of FOXO1a nuclear export.

[reaction: see text] Two inhibitors of FOXO1a-mediated nuclear export, psammaplysenes A and B, have been synthesized by a flexible and efficient route. A common starting material, 4-iodophenol, was used to prepare both halves of these pseudosymmetric dibromotyrosine-derived metabolites.

Coil-to-helix transition and ligand release of Bombyx mori pheromone-binding protein.

The transport of hydrophobic insect pheromones through the aqueous medium surrounding their receptors is assisted by pheromone-binding proteins (PBPs). The protein from the silkworm moth Bombyx mori, BmorPBP, exhibits a pH-dependent conformational change postulated to trigger the release of the pheromone bombykol to its receptor. At low pH, an alpha-helix occupies the same binding pocket that houses the pheromone in the BmorPBP-bombykol complex at high pH.

N-acyl derivatives of arginine and tryptophan isolated from environmental DNA expressed in Escherichia coli.

Heterologous expression of microbial DNA extracted directly from environmental samples (environmental DNA, eDNA) in easily cultured hosts can provide access to natural products produced by previously uncultured bacteria. This report describes the characterization of antibacterially active long-chain N-acyl derivatives of tryptophan and arginine that are produced by eDNA clones hosted in Escherichia coli. The sequencing and subcloning of the proposed N-acyl amino acid synthases (NASs) for each family of natural products are also described.

Bacterial printing press that regenerates its ink: contact-printing bacteria using hydrogel stamps.

This paper describes the use of micropatterned agarose stamps prepared by molding against PDMS masters to print patterns of bacteria on agar plates. Topographically patterned agarose stamps were inked with suspensions of bacteria; these stamps generated patterns of bacteria with features as small as 200 microm over areas as large as 50 cm2. Stamps with many small features (>200 microm) were used to study patterns of bacteria growing on media containing gradients of small molecules; stamps with larger features (>750 microm) were used to print different strains of bacteria simultaneously.

The psammaplysenes, specific inhibitors of FOXO1a nuclear export.

A small collection of marine natural product extracts was screened for compounds that would compensate lost tumor suppressor functionality in PTEN-deficient cells. From the most active extract, the previously unreported bromotyrosine derivative, psammaplysene A (1), was identified. Psammaplysene A compensates for PTEN loss by relocalizing the transcription factor FOXO1a to the nucleus.

Residents' perception of effectiveness of twelve evaluation methods for measuring competency.

Objective: The authors assessed residents' perceptions of techniques used to evaluate competency.

Methods: Psychiatry residents from a single program rated 12 evaluation techniques for their effectiveness to measure resident competency. They rated each method for 25 selected skills reflecting the six general competencies.

Lessons from natural molecules.

Natural products have inspired chemists and physicians for millennia. Their rich structural diversity and complexity has prompted synthetic chemists to produce them in the laboratory, often with therapeutic applications in mind, and many drugs used today are natural products or natural-product derivatives. Recent years have seen considerable advances in our understanding of natural-product biosynthesis.

Demonstration of portfolios to assess competency of residents.

Residency educators are identifying approaches to measure resident competence. Portfolios are well suited since they require work already completed as part of patient care where competency must be demonstrated. This paper describes assessment of the reliability and validity of portfolios in a psychiatry residency program.

Long-chain N-acyltyrosine synthases from environmental DNA.

The heterologous expression of DNA extracted directly from environmental samples (environmental DNA [eDNA]) in easily cultured hosts provides access to natural products produced by previously inaccessible microorganisms. When eDNA cosmid libraries were screened in Escherichia coli for antibacterially active clones, long-chain N-acyltyrosine-producing clones were found in every eDNA library. These apparently common natural products have not been previously described from screening extracts of cultured bacteria for biologically active natural products.

Can one portfolio measure the six ACGME general competencies?

Objective: To determine that portfolios, useable by any program, can provide needed evidence of resident performance within the ACGME general competencies.

Methods: Eighteen residents constructed portfolios with selected entries from thirteen psychiatric skills. Two raters assessed whether entries reflected resident performance within the general competencies.

Palmitoylputrescine, an antibiotic isolated from the heterologous expression of DNA extracted from bromeliad tank water.

Heterologous expression of large fragments of microbial DNA extracted directly from environmental samples (environmental DNA, or eDNA) in easily cultured hosts should provide access to some of the natural products produced by previously uncultured bacteria. The natural product antibiotic palmitoylputrescine (1) was isolated from Escherichia coli transformed with a cosmid (pCSLF16) containing DNA extracted directly from Costa Rican bromeliad tank water. In this report we describe the characterization of this antibiotic and its biosynthetic gene.

Biopsychosocial formulation: recognizing educational shortcomings.

Objective: Since Engel introduced the biopsychosocial model, it has been extensively examined. The authors expect psychiatrists to formulate cases using the biopsychosocial model. However, resident psychiatrists' ability to generate formulations using this model has received little attention.