Long after its alleged demise, phlogiston was still presented, discussed and defended by leading chemists. Even some of the leading proponents of the new chemistry admitted its 'absolute existence'. We demonstrate that what was defended under the title 'phlogiston' was no longer a particular hypothesis about combustion and respiration. Rather, it was a set of ontological and epistemological ass...

Legionella pneumophila, the causative agent of Legionnaire's disease, uses its type IV secretion system to translocate over 300 effector proteins into host cells. These effectors subvert host cell signaling pathways to ensure bacterial proliferation. Despite their importance for pathogenesis, the roles of most of the effectors are yet to be characterized. Key to understanding the function of ef...

Acidobacterium capsulatum is an acid-tolerant, encapsulated, Gram-negative member of the ubiquitous, but poorly understood Acidobacteria phylum. Little is known about the genetics and regulatory mechanisms of A. capsulatum. To begin to address this gap, we identified the gene encoding the A. capsulatum major sigma factor, rpoD, which encodes a 597-amino acid protein with a predicted sequence hi...

The principal bridge connecting the erythrocyte membrane to the spectrin-based skeleton is established by band 3 and ankyrin; mutations leading to reduced bridge formation or increased bridge rupture result in morphological and mechanical abnormalities. Because membrane mechanical properties are determined in part by the protein interactions that stabilize the membrane, we have evaluated the ra...

The important plant hormone salicylic acid (SA; 2-hydroxybenzoic acid) regulates several key plant responses including, most notably, defence against pathogens. A key enzyme for SA biosynthesis is isochorismate synthase (ICS), which converts chorismate into isochorismate, and for which there are two genes in Arabidopsis thaliana One (AtICS1) has been shown to be required for increased SA biosyn...

Many recombinant proteins are produced as a fusion protein tagging hexahistidine, which has been used for studying their biological function both in vitro and in vivo. Unexpectedly, we observed activation of BALB/c mouse splenocytes when treated with hexahistidine-tagged recombinant proteins. This activation was hexahistidine-specific since the anti-pentahistidine antibody completely neutralize...

Fyn-related kinase (Frk) was first identified using human breast cancer cells. It shares 51% identity with c-Src. Like all members of the Src family, Frk is thought to cause several cancers via dysregulations in signal transduction from cell-surface receptors. The excess activity of Frk on beta-cells has a crucial role in type-I diabetes. A silent mutation at Ile229 conferred a bacterial expres...

RgpA and Kgp gingipains are non-covalent complexes of endoprotease catalytic and hemagglutinin-adhesin domains on the surface of Porphyromonas gingivalis. A motif conserved in each domain has been suggested to function as an oligomerization motif. We tested this hypothesis by mutating motif residues to hexahistidine or insertion of hexahistidine tag to disrupt the motif within the Kgp catalytic...

The movement proteins of two tobamoviruses (tobacco mosaic virus, TMV, common strain U1 and cruciferous TMV strain) containing amino-terminal hexahistidine affinity tags were overexpressed in Escherichia coli and purified by metal chelate affinity chromatography. Purified recombinant proteins were immobilized to a Ni(2+)-chelate adsorbent and their ability to interact with full-length genomic T...

Salmonella thin aggregative fimbriae (Tafi; curli) are important in pathogenesis and biofilm formation; however, less is known of their structure and morphogenesis. In the Salmonella agfBAC Tafi operon, the transcription and role of agfC have been elusive. In this study, agfBAC transcripts were detected using a sensitive reverse transcriptase technique. Native AgfC was not detected using polycl...