Magnesium Transport in Bacillus subtilis W23 During Growth and Sporulation
AUTOR(ES)
Scribner, Harvey
RESUMO
The active transport of magnesium by cells of Bacillus subtilis strain W23 occurs by a highly specific transport system (Mg2+ is favored over Mn2+, Co2+, or Ca2+) that is energy dependent (i.e., glucose is required in minimal medium and the system is inhibited by cyanide and m-chlorophenyl carbonylcyanidehydrazone). The rate of magnesium uptake by log-phase B. subtilis cells follows saturation kinetics with a Km of 2.5 × 10−4 M and a Vmax of 4.4 μmol per min per g (dry weight) at 30 C. Manganese is a competitive inhibitor showing a Ki of 5 × 10−4 M. During sporulation the rate of magnesium transport declines. This decline in rate is specific for the magnesium system as the manganese and calcium transport rates increase. The residual magnesium transport function in sporulating cells shows both an altered Km and an altered Vmax. The magnesium content of late sporulating cells is also lower than that for log-phase cells.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=246605Documentos Relacionados
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