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Author(s): Christopher F. Higgins (corresponding author) [1, 2] The acquisition of multidrug resistance is a serious impediment to improved healthcare. Multidrug resistance is most frequently due to active transporters that [...]

Bacteria have developed antibiotic-resistance mechanisms, and LmrA, a protein in Lactococcus lactis, extrudes amphiphilic compounds from the cytoplasmic membrane, to mediate antibiotic resistance. LmrA is an ATP-binding cassette (ABC) transporter, along with the human multidrug-resistance P-glycoprotein. LmrA was expressed in human ling fibroblast cells, which was surprisingly targeted to the plasma membrane, conferring typical multi-drug resistance. Their pharmacological characteristics were similar and their affinity for vinblastine and magnesium-ATP was indistinguishable.

Enolase and RhlB, a member of the DEAD-box family of ATP-dependent RNA helicases, are novel components of RNA degradosome. RhlB most likely unwinds distinct RNA structures in the presence of ATP to facilitate mRNA degradation by PNPase as shown by the RNAs failure to degrade when RhlB is blocked by an affinity-purified antibody even if ATP is added. Enolase's purpose in degradosome is still unknown.

There is a family of proteins that bind adenosine triphosphate (ATP), a molecule involved in the production of energy, which are also involved in the transport of molecules. This group of proteins includes molecules of bacteria involved in the uptake and export of molecules. In higher organisms, they include genes involved in resistance to multiple types of drugs used in tumor therapy; in resistance to the drug chloroquine in the malarial parasite; the transport of a yeast mating pheromone; and the gene that is defective in cystic fibrosis. Structural models are presented of these ATP-binding transport molecules. In almost 70 percent of the patients with cystic fibrosis, deletions are present in the areas of the gene that are involved in binding and degrading of ATP. Many of the symptoms of cystic fibrosis stem from abnormally thick secretions, especially in the lungs. These symptoms are related to a problem in the transport of chloride ions (electrically charged particles) across cellular membranes. Thus, it was thought that the defective gene in cystic fibrosis might encode a protein that works as a channel that ions pass through. However, some researchers believe that the defective protein in cystic fibrosis is not a channel for chloride molecules. Channels do not require the degradation of ATP. Chloride channels allow the flow of chloride ions in both directions, while the proteins that the gene involved in cystic fibrosis encodes only allow the flow of ions in one direction. Other evidence that indicates the gene does not code for a chloride channel includes: the size of the molecule, which is too large; chloride channels vary in different tissues, but there is only one defective gene in cystic fibrosis; and other characteristic sequences of chloride channels are not present. Therefore, it is thought that the protein is not a chloride channel, but may transport a molecule that regulates a chloride channel. (Consumer Summary produced by Reliance Medical Information, Inc.)

The common bacterium Escherichia coli and its bacterial viruses are well used in science research because they have ideal pathogenic, and nutritional characteristics. However, the functions of up to 40% of an estimated 4,288 genes in E. coli have not yet been established. Scientists need to launch a cooperative international research strategy to ascertain the bacterium's genetic makeup.