Automated streak-seeding with micromachined silicon tools.

This report presents a new approach to streak-seeding based on custom-designed silicon microtools. Experimental data show that the microtools produce similar results to the commonly used boar bristles. One advantage to using silicon is that it is rigid and can easily serve as an accurately calibrated end-effector on a micro-robotic system.

Crystal structures of catalytic complexes of the oxidative DNA/RNA repair enzyme AlkB.

Nucleic acid damage by environmental and endogenous alkylation reagents creates lesions that are both mutagenic and cytotoxic, with the latter effect accounting for their widespread use in clinical cancer chemotherapy. Escherichia coli AlkB and the homologous human proteins ABH2 and ABH3 (refs 5, 7) promiscuously repair DNA and RNA bases damaged by S(N)2 alkylation reagents, which attach hydrocarbons to endocyclic ring nitrogen atoms (N1 of adenine and guanine and N3 of thymine and cytosine). Although the role of AlkB in DNA repair has long been established based on phenotypic studies, its exact biochemical activity was only elucidated recently after sequence profile analysis revealed it to be a member of the Fe-oxoglutarate-dependent dioxygenase superfamily.

Crystal structures of two bacterial 3-hydroxy-3-methylglutaryl-CoA lyases suggest a common catalytic mechanism among a family of TIM barrel metalloenzymes cleaving carbon-carbon bonds.

The enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) lyase catalyzes the terminal steps in ketone body generation and leucine degradation. Mutations in this enzyme cause a human autosomal recessive disorder called primary metabolic aciduria, which typically kills victims because of an inability to tolerate hypoglycemia. Here we present crystal structures of the HMG-CoA lyases from Bacillus subtilis and Brucella melitensis at 2.

The 2.35 A structure of the TenA homolog from Pyrococcus furiosus supports an enzymatic function in thiamine metabolism.

TenA (transcriptional enhancer A) has been proposed to function as a transcriptional regulator based on observed changes in gene-expression patterns when overexpressed in Bacillus subtilis. However, studies of the distribution of proteins involved in thiamine biosynthesis in different fully sequenced genomes have suggested that TenA may be an enzyme involved in thiamine biosynthesis, with a function related to that of the ThiC protein. The crystal structure of PF1337, the TenA homolog from Pyrococcus furiosus, is presented here.

Gain of structure and IgE epitopes by eukaryotic expression of the major Timothy grass pollen allergen, Phl p 1.

Approximately 400 million allergic patients are sensitized against group 1 grass pollen allergens, a family of highly cross-reactive allergens present in all grass species. We report the eukaryotic expression of the group 1 allergen from Timothy grass, Phl p 1, in baculovirus-infected insect cells. Domain elucidation by limited proteolysis and mass spectrometry of the purified recombinant glycoprotein indicates that the C-terminal 40% of Phl p 1, a major IgE-reactive segment, represents a stable domain.

The SufE sulfur-acceptor protein contains a conserved core structure that mediates interdomain interactions in a variety of redox protein complexes.

The isc and suf operons in Escherichia coli represent alternative genetic systems optimized to mediate the essential metabolic process of iron-sulfur cluster (Fe-S) assembly under basal or oxidative-stress conditions, respectively. Some of the proteins in these two operons share strong sequence homology, e.g.

The 2.3-A crystal structure of the shikimate 5-dehydrogenase orthologue YdiB from Escherichia coli suggests a novel catalytic environment for an NAD-dependent dehydrogenase.

We present here the 2.3-A crystal structure of the Escherichia coli YdiB protein, an orthologue of shikimate 5-dehydrogenase. This enzyme catalyzes the reduction of 3-dehydroshikimate to shikimate as part of the shikimate pathway, which is absent in mammals but required for the de novo synthesis of aromatic amino acids, quinones, and folate in many other organisms.