CLONING AND EXPRESSION OF TRANSALDOLASE FROM POTATO

We have isolated a cDNA encoding transaldolase, an enzyme of the pento se-phosphate pathway, from potato (Solanum tuberosum). The 1.5 kb cDNA encodes a protein of 438 amino acid residues with a molecular mass of 47.8 kDa. When the potato cDNA was expressed in Escherichia coli a 45 kDa protein with transaldolase activity was produced. The first 62 am ino acids of the deduced amino acid sequence represent an apparent pla stid transit sequence. While the potato transaldolase has considerable similarity to the enzyme from cyanobacteria and Mycobacterium leprae, similarity to the conserved transaldolase enzymes from humans, E. col i and Saccharomyces cerevisiae is more limited. Northern analysis indi cated that the transaldolase mRNA accumulated in tubers in response to wounding. Probing the RNA from various potato tissues indicated that the transaldolase mRNA accumulation to higher levels in the stem of ma ture potato plants than in either leaves or tubers. These data are con sistent with a role for this enzyme in lignin biosynthesis.