Article Abstract:
The cryptic ushA gene (ushA(super.c)) in Salmonella enterica natural isolates (serotype Typhimurium) has been seen to be inactivated by a single missense mutation, the first reported gene inactivation in natural isolates of bacteria via a missense mutation. Results indicate the evolution of new enzymes involving a silent gene which produces an relatively inactive or inactive product. They also indicate evolution of a novel, although unknown, enzyme specificity by one amino acid change.
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Article Abstract:
Nucleotide sequencing of the L-asparagine permease gene (ansP) obtained during recombinant clone screening from a cosmid library of Salmonella enterica reveals the presence of 497 amino acid residues with 12 putative transmembrane segments in the polypeptide gene product with a 54 kDa molecular mass. The deduced amino acid sequence is homologous to a basic and aromatic amino acid permease family. L-aspargine uptake is significantly higher in ansP-containing strains than in control strains.
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Article Abstract:
A study was conducted on the exponential-phase expression of spvA of the Salmonella typhimurium virulence plasmid to determine if cessation of growth was required for induction. The findings indicate that since the induction of the spv genes happens intracellularly during exponential growth of salmonellae, cessation of growth may not be the most important inducing signal for spv gene expression.
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