Reddish<i>Escherichia coli</i>Cells Caused by Overproduction of<i>Bacillus stearothermophilus</i>Uroporphyrinogen III Methylase: Cloning, Sequencing, and Expression of the Gene

Abstract

During shotgun cloning of an amylase gene, we found a transformant of Escherichia coli with a reddish color. The transformant produced highly water-soluble red pigments the molecular masses of which were less than 3000. The plasmid harbored by the transformant contained a DNA fragment derived from a strain of Bacillus stearothermophilus. Truncation of the insert DNA showed that an 1.1-kbp Sau 3A-SalI fragment was responsible for the reddish colony. An open reading frame was found in the nucleotide sequence of the 1.1-kbp DNA fragment. The production of the red pigment was accompanied by a colorless 28-kDa protein. The sequence of the 28-kDa protein was highly homologous to bacterial uroporphyrinogen III methylases participating in corrinoid biosynthesis. The 28-kDa protein was found to be a thermostable uroporphyrinogen III methylase.