CLONING OF A MARINE CYANOBACTERIAL PROMOTER FOR FOREIGN GENE-EXPRESSION USING A PROMOTER PROBE VECTOR

A marine cyanobacterial promoter was cloned to allow efficient foreign gene expression. This was carried out using chloramphenicol acetyl tr ansferase (CAT) as a marker protein. For rapid and simple measurement of CAT activity, a method based on a fluorescently labeled substrate w as improved by utilizing HPLC equipped with a flow-through fluorescent spectrophotometer. This method was used in conjunction with a newly c onstructed promoter probe vector. Cyanobacterial transformants, harbor ing plasmid containing a cloned 2-kbp marine cyanobacterial genomic fr agment, showed a 10-fold higher CAT activity, compared with that achie ved using the kanamycin-resistant gene promoter. From the sequence ana lysis of the cloned fragment, a putative promoter region was found.