Metabolism of Phosphonoacetate as the Sole Carbon and Phosphorus Source by an Environmental Bacterial Isolate

A gram-negative bacterium isolated from activated sludge was able to utilize up to 25 mM phosphonoacetate as the sole carbon and phosphorus source, with simultaneous excretion of virtually equimolar levels of phosphate. 2-Aminoethylphosphonate was similarly utilized with equivalent growth rates and cellular yields, while 3-aminopropyl-, 4-aminobutyl-, methyl-, ethyl-, and phenylphosphonates served only as phosphorus sources.     

Interdomain but not intermolecular interactions observed in CFTR channels.

Gating of the cystic fibrosis transmembrane conductance regulator (CFTR) channels requires interdomain and/or intermolecular interactions involving different parts of the protein, yet the exact nature of those interactions remains unclear. In this study we report that treating wild type CFTR-expressing cells with oxidizing agents results in a significant reduction in the gel mobility of the protein indicative of the formation of disulfide bonds. In contrast, mutant CFTR channels in which cysteine residues in both nucleotide binding domains (NBDs) were mutated to serine, showed little change in gel mobility in oxidizing conditions. Mutation of the two cysteine residues in either the first or the second NBD alone also eliminates the change in gel mobility in oxidizing conditions. Wild type channels treated with oxidizing agents did not appear to form disulfide bonds with other proteins, suggesting that the close association that allows the formation of disulfide bonds occurs only within single proteins and not between separate channels interacting in a multimer.