%0 Journal Article %A Warner, Jessica B. %A Lolkema, Juke S. %T Growth of Bacillus subtilis on citrate and isocitrate is supported by the Mg2+–citrate transporter CitM %D 2002 %J Microbiology, %V 148 %N 11 %P 3405-3412 %@ 1465-2080 %R https://doi.org/10.1099/00221287-148-11-3405 %K promoter fusion %K exchange %K TCA, tricarboxylic acid %K membrane vesicles %K TCA cycle intermediate %K FCCP, carbonylcyanide p-trifluormethoxy-phenylhydrazone %K divalent metal ion–citrate complex %K RSO, right-side-out %K MSMYE, minimal salts medium/0·05% yeast extract %I Microbiology Society, %X Bacillus subtilis 168 was assayed for its growth on tricarboxylic acid (TCA) cycle intermediates and related compounds as the sole carbon sources. Growth of the organism was supported by citrate, D-isocitrate, succinate, fumarate and L-malate, whereas no growth was observed in the presence of cis-aconitate,2-oxoglutarate, D-malate, oxaloacetate and tricarballylate. Growth of the organism on the tricarboxylates citrate and D-isocitrate required the presence of functional CitM, an Mg2+–citrate transporter, whereas its growth on succinate, fumarate and L-malate appeared to be CitM-independent. Interestingly, the naturally occurring enantiomer D-isocitrate was favoured over L-isocitrate by the organism. Like citrate, D-isocitrate was shown to be an inducer of citM expression in B. subtilis. The addition of 1 mM Mg2+ to the growth medium improved growth of the organism on both citrate and D-isocitrate, suggesting that D-isocitrate was taken up by CitM in complex with divalent metal ions. Subsequently, the ability of CitM to transport D-isocitrate was demonstrated by competition experiments and by heterologous exchange in right-side-out membrane vesicles prepared from E. coli cells expressing citM. None of the other TCA cycle intermediates and related compounds tested were recognized by CitM. Uptake experiments using radioactive 63Ni2+ provided direct evidence that D-isocitrate is transported in complex with divalent metal ions. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-148-11-3405