Deletion of lysine 84 to lysine 89 enhances the cytotoxicity and the receptor binding affinity of human lymphotoxin.
Human lymphotoxin (hLT) and its mutant genes have been constructed by in vitro mutagenesis and expressed in Escherichia coli. A deletion of Lys84 to Lys89 in hLT remarkably enhanced both the cytotoxicity against human WiDr cells (colon adenocarcinoma cell line) and the prostaglandin E2-inducing activity toward human synovial cells by approximately 1000- and 50-fold, respectively. The enhanced biological potency coincided with an increase of receptor binding affinity. Circular dichroism studies and the heat and folding stabilities were similar to those of the native form. We propose that the region of Lys84 to Lys89 forms a loop structure at the hLT molecular surface and plays an important role in modulating the receptor binding and biological activities of hLT.
Wakabayashi
T
T
Tsukuba Research Laboratories, Eisai Co., Ltd., Ibaraki, Japan.
Asada
M
M
Nagasu
T
T
Iijima
A
A
Hasegawa
Y
Y
Shikata
Y
Y
Kitoh
K
K
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D002872:Chromosome Deletion; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D005822:Genetic Vectors; D006801:Humans; D007700:Kinetics; D008233:Lymphotoxin-alpha / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D008239:Lysine; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D008233:Lymphotoxin-alpha; D011956:Receptors, Cell Surface; D008239:Lysine