title: Selective assimilation of selenite by Escherichia coli.
abstract: The assimilation of selenite by Escherichia coli involves a transport process specific for this anion. Cystine, a repressor of sulfate and selenite uptake, when added to the growth medium, had no effect on selenite uptake; nor did sulfite inhibit assimilation of selenite. Cells grown aerobically in a basic salts medium transported selenite at an initial rate of 0.14 mumol . g-1 min-1 and a Vmax of 393.0 mumol. g-1 . min-1. In contrast, cells grown in a medium that contained the trace elements necessary for synthesis of the selenoenzyme formate dehydrogenase took up selenite at a significantly faster rate (initial rate = 0.27 mumol . g-1 . min-1, Vmax = 658.2 mumol . g-1 . min-1). Km values for the transport process in the two media, however, were found to be similar. The results suggest the existence of a metabolic pathway, specific for selenite, responsible for the incorporation of selenium into formate dehydrogenase.U
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D003553:Cystine / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism*; D007700:Kinetics; D020887:Selenious Acid; D012643:Selenium / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism; D013447:Sulfites / Q000378:metabolism; D013691:Tellurium / Q000494:pharmacology; D013885:Thiosulfates / Q000494:pharmacology
chemical_list: D013431:Sulfates; D013447:Sulfites; D013885:Thiosulfates; C012036:sodium sulfate; D003553:Cystine; D020887:Selenious Acid; D012643:Selenium; C026660:tellurous acid; D013691:Tellurium; C025026:sodium sulfite