Modification Of A New Antitumor Antibiotic C1027 Apoprotein By Genetic Engineering

Macromolecular antitumor antibiotic are currently the focus of intense research in the fields of chemistry, biology and medical sciences, because of their unusual molecular structure and potent biological activities. C1027, discovered in our institute in 1988, is a new macromolecular peptide antitumor antibiotic with highly potent cytotoxicity to cultured cancer cells and marked DNA cleaving ability. The molecule of C1027 is composed of an apoprotein which consists of 110 amino acid residues and an enediyene chromophore through non-covalent binding. Its molecular weight is 10500 Da for the apoprotein and 845 Da for the chromophore respectively. C1027 inhibits mainly DNA synthesis and causes DS and SS DNA cleavage without any supplement of reducing agents. However, C1027 is a macromolecular substance, and may cause immunological reaction. So, it is very important to reduce the size of the molecule. On the other hand, C1027 is a promising effector agent for the manufacturing of immunoconjugate for cancer targeting therapy. The molecular weight of C1027 is much smaller than that of ricin, Pseudomonas exotoxin (PE) or Diphtheria toxin (DT). However, C1027 is still a relatively large molecule. Further reduction of its molecular weight should be useful for downsizing of immumoconjugate molecule. In this study, We modified C1027 molecule by genetic engineering. C1027 apoprotein was truncated by deletion of 16 amino acids from its C-terminus. A new C1027 molecule with highly potent antitumor activity was obtained by reconstitution of the truncated, engineered apoprotein and chromophore.Total DNA from the C1027 producing stain, Streptomyces globisporus C1027, was extracted as the template, and the gene, Apo C1027(94), coding for N-terminal 94 amino acids and signal peptide sequence of...