TY - JOUR
T1 - Mutational analysis of the histidine operon promoter of Salmonella typhimurium
AU - Shand, R. F.
AU - Blum, P. H.
AU - Holzschu, D. L.
AU - Urdea, M. S.
AU - Artz, S. W.
PY - 1989
Y1 - 1989
N2 - We isolated a collection of 67 independent, spontaneous Salmonella typhimurium his operon promoter mutants with decreased his expression. The mutants were isolated by selecting for resistance to the toxic lactose analog o-nitrophenyl-β-D-thiogalactoside in a his-lac fusion strain. The collection included base pair substitutions, small insertions, a deletion, and one large insertion identified as IS30 (IS121), which is resident on the Mu d1 cts(Ap(r)lac) phage used to construct the his-lac fusion. Of the 37 mutations that were sequenced, 14 were unique. Six of the 14 were isolated more than once, with the IS30 insertion occurring 16 times. The mutations were located throughout the his promoter region, with two in the conserved -35 hexamer sequence, four in the conserved -10 hexamer sequence (Pribnow box), seven in the spacer between the -10 and -35 hexamer sequences, and the IS30 insertions just upstream of the -35 hexamer sequence. Four of the five substitution mutations changed a consensus base pair recognized by Eσ70 RNA polymerase in the -10 or -35 hexamer. Decreased his expression caused by the 14 different his promoter mutations was measured in vivo. Relative to the wild-type promoter, the mutations resulted in as little as a 4-fold decrease to as much as a 357-fold decrease in his expression, with the larges decreases resulting from changes in the most highly conserved features of Eσ70 promoters.
AB - We isolated a collection of 67 independent, spontaneous Salmonella typhimurium his operon promoter mutants with decreased his expression. The mutants were isolated by selecting for resistance to the toxic lactose analog o-nitrophenyl-β-D-thiogalactoside in a his-lac fusion strain. The collection included base pair substitutions, small insertions, a deletion, and one large insertion identified as IS30 (IS121), which is resident on the Mu d1 cts(Ap(r)lac) phage used to construct the his-lac fusion. Of the 37 mutations that were sequenced, 14 were unique. Six of the 14 were isolated more than once, with the IS30 insertion occurring 16 times. The mutations were located throughout the his promoter region, with two in the conserved -35 hexamer sequence, four in the conserved -10 hexamer sequence (Pribnow box), seven in the spacer between the -10 and -35 hexamer sequences, and the IS30 insertions just upstream of the -35 hexamer sequence. Four of the five substitution mutations changed a consensus base pair recognized by Eσ70 RNA polymerase in the -10 or -35 hexamer. Decreased his expression caused by the 14 different his promoter mutations was measured in vivo. Relative to the wild-type promoter, the mutations resulted in as little as a 4-fold decrease to as much as a 357-fold decrease in his expression, with the larges decreases resulting from changes in the most highly conserved features of Eσ70 promoters.
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U2 - 10.1128/jb.171.11.6330-6337.1989
DO - 10.1128/jb.171.11.6330-6337.1989
M3 - Article
C2 - 2553676
AN - SCOPUS:0024452244
VL - 171
SP - 6330
EP - 6337
JO - Journal of Bacteriology
JF - Journal of Bacteriology
SN - 0021-9193
IS - 11
ER -