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KMID : 0903519920350040325
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Journal of the Korean Society of Agricultural Chemistry and Biotechnology
1992 Volume.35 No. 4 p.325 ~ p.325
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Characterization of xylose isomerase promoter in Escherichia coli
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강병태
이인구/노동현
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Abstract
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The expression of xylose isomerase(xylA) was induced in the presence of xylose on E. cali JM109. The expression of xylose isomerase was also induced by xylose in xylA mutant DH 77 harboring multicopy number plasmid pEX202 and low copy number plasmid pEX102 which contained xylA gene but there is not a great difference of activity between the copy numbers. We assume that the expression of xylA may be severely controlled by the titration of xylR in chromosome. To characterize the regulation of the expression of xylA gene, xylA promoter-CAT (Pxyl-CAT) fusion gene and xylA promoter-lacZ (Pxyl-lacZ) fusion gene were constructed on the multicopy plasmids, from which the xylA promoter located on a 200 base pair (bp) DNA fragment in upstream of xylA structural gene. The expression of chloramphenicol resistance and β-galactosidase in fusion genes were induced by xylose and repressed by glucose, respectively. Glucose repression β-galactosidase in Pxyl-lacZ fusion gene was reversed by t1e addition of cAMP same as xyl A gene. This results demonstrated that the expression of fusion gene was controlled by xylA promoter region and positively regulated by xylR product. The regulation site of xylA promter in 75 base pairs segment was deduced by deletion analysis of the xylA promoter which located in 79 by upsteam from the initiation site of xylA translation. The specific sequence between -114bp and -110bp at upstream of the initiation site of xylA translation may be serves as binding site for CRP-cAMP complex because its sequence showed homology of the consensus sequence of CRP binding.
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