| Research Abstract |
Genes structures of pectate lyase and pectin lyase of Erwinia carotovora Er, their expression and regulation and excretion of pectate lyases from the cells were studied in this research. Firstly, pectate lyase gene II was cloned and the complete nucleotides of pectate lyase gene II were sequenced in addition to pectate lyase genes I and III which were already determined. Complete nucleotides of pectate lyase I were also sequenced and some sequences were revised. Pectate lyase genes I.II.III were found to be closely and tandemly lined as a cluster. Secondly, the complete nucleotides of pectin lyase gene were sequenced, and found to be composed of 942 bp. From this result, pectin lyase was considered to be a protein of molecular mass of 33,700 composed of 314 amino acid residues. Regions of -35, -30, SD sequence and two parindromic regions were found in the 5'upstream of pectin lyase. However, Lex A binding site which is found in operator region of SOS regulon of E.coli. From the experiment using the deletion mutants in the 5'upstream region of pectin lyase, expression of pectin lyase genes seemed to be not controlled by repressor as in SOS reaction. Thirdly, pectate lyases I,II,III were not excreated from the cells of E.coli, while they were excreated efficiently from the cells of Erwinia carotovora Er. Further experiments are necessary to explain this difference.
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