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The Last Gene of the fla/che Operon in Bacillus subtilis, ylxL, Is Required for Maximal  D
Function.H. Werhane, 2004.ylxL was found to be the last gene of the fla/che operon in Bacillus subtilis and is cotranscribed with the gene for the flagellum-specific alternate sigma factor, D .
The ylxL gene was disrupted by insertional mutagenesis, and
the resultant mutant strain was found to be compromised for
D-dependent
functions .
Evidence for a Fourth Hydrogenase in Desulfovibrio fructosovorans. Laurence Casalot, 2002.A strain devoid of the three hydrogenases characterized for Desulfovibrio fructosovorans was constructed using marker exchange mutagenesis . As expected, the H2-dependent methyl viologen reduction activity of the strain was null, but physiological studies showed no striking differences between the mutated and wild-type strains . The H+-D2 exchange activity measured in the mutated strain indicates the presence of a fourth hydrogenase in D . fructosovorans . Three Transporters Mediate Uptake of Glycine Betaine and Carnitine by Listeria monocytogenes in Response to Hyperosmotic Stress. Apostolos S. Angelidis, 2003.The uptake and accumulation of the potent osmolytes glycine betaine and carnitine enable the food-borne pathogen Listeria monocytogenes to proliferate in environments of elevated osmotic stress, often rendering salt-based food preservation inadequate . To date, three osmolyte transport systems are known to operate in L . monocytogenes: glycine betaine porter I (BetL), glycine betaine porter II (Gbu), and a carnitine transporter OpuC . We investigated the specificity of each transporter towards each osmolyte by creating mutant derivatives of L . monocytogenes 10403S that possess each of the transporters in isolation . Kinetic and steady-state osmolyte accumulation data together with growth rate experiments demonstrated that osmotically activated glycine betaine transport is readily and effectively mediated by Gbu and BetL and to a lesser extent by OpuC . Osmotically stimulated carnitine transport was demonstrated for OpuC and Gbu regardless of the nature of stressing salt . BetL can mediate weak carnitine uptake in response to NaCl stress but not KCl stress . No other transporter in L . monocytogenes 10403S appears to be involved in osmotically stimulated transport of either osmolyte, since a triple mutant strain yielded neither transport nor accumulation of glycine betaine or carnitine and could not be rescued by either osmolyte when grown under elevated osmotic stress .
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