Ehrlichia chaffeensis, an obligatory intracellular gram-negative bacterium, must take up various nutrients and metabolic compounds because it lacks many genes involved in metabolism. Nutrient uptake by a gram-negative bacterium occurs primarily through pores or channels in the bacterial outer membrane. Here we demonstrate that isolated E. chaffeensis outer membranes have porin activities, as de...

Neisseria gonorrhoeae has two porins, PIA and PIB, whose genes (porA and porB, respectively) are alleles of a single por locus. We recently demonstrated that penB mutations at positions 120 and 121 in PIB, which are presumed to reside in loop 3 that forms the pore constriction zone, confer intermediate-level resistance to penicillin and tetracycline (M. Olesky, M. Hobbs, and R. A. Nicholas, Ant...

We investigated the unusual susceptibility to meropenem observed for seven imipenem-resistant clinical isolates of Pseudomonas aeruginosa. These strains were genetically closely related, expressed OprD, as determined by Western blot analyses, and were resistant to imipenem (>5 microg/ml) but susceptible to meropenem (<1 microg/ml). The oprD genes from two isolates were entirely sequenced, and t...

The isolate major outer membrane protein from Rhodopseudomonas capsulata St. Louis (ATCC 23782) has a high porin activity in reconstituted phospholipid liposomes. The pore size of the homooligomeric porin with subunits of Mr 33,000 was determined to be about 0.8 nm in radius. Circular dichroism data revealed major portions of the beta structure. Heating of the oligomer resulted in monomer forma...

This paper describes AQUA, a question answering system. AQUA combines Natural Language processing (NLP), Ontologies, Logic, and Information Retrieval technologies in a uniform framework. AQUA makes intensive use of an ontology (which encode knowledge) in several parts of the question answering system. The ontology is used in the refinement of the initial query, the reasoning process (a generali...

We made single and combined mutations in ompU, ompT, and the two putative porin genes vca1008 and vc0972. The fitness of the strains was tested in vitro and in the infant mouse model of intestinal infection. We also studied the transcriptional induction of vca1008 in vitro and during mouse infection. We show that vca1008 is induced during infection and is necessary and sufficient (in the absenc...

A carbapenem resistant but ceftriaxone and cefepime susceptible Klebsiella oxytoca was isolated from the blood of a patient with polymicrobial bacteremia after 2 weeks of ertapenem treatment. Whole-genome sequencing identified no carbapenemase gene nor plasmid, but only blaOXY-2-8 gene with a mutation in the promoter that's been reported to increase its expression. Two other specific carbapenem...

Titanium is biocompatible and widely utilized in a variety of applications. Recently, titanium in pico-nanometer scale and soluble form (Aqua Titan) has expanded its use to applied human health and performance. The purpose of this article is to review the current evidence associated with specific physiological responses to Aqua Titan-treated materials. In vitro studies have shown that applicati...

The specific recognition by mitochondria of the precursor of porin and the insertion into the outer membrane were studied with a radiolabeled water-soluble form of porin derived from the mature protein. High-affinity binding sites had a number of 5-10 pmol/mg mitochondrial protein and a ka of 1-5 X 10(8) M-1. Binding was abolished after trypsin pretreatment of mitochondria indicating that bindi...

Precise information regarding the transmembrane topology of mitochondrial porin is essential for understanding the mechanisms by which this protein functions. Porin acts as a channel in the outer membrane and interacts with small solutes and proteins to regulate mitochondrial function. The acquisition of high-resolution structural data requires a method of maintaining high concentrations of una...