Df. Revell et al., NUCLEOTIDE-SEQUENCE AND EXPRESSION IN ESCHERICHIA-COLI OF CDNAS ENCODING PAPAYA PROTEINASE OMEGA FROM CARICA-PAPAYA, Gene, 127(2), 1993, pp. 221-225
We have cloned and sequenced two similar, but distinct, cDNAs from bot
h fruit and leaf tissues of Carica papaya. The C-terminal portion of t
he predicted amino acid (aa) sequence of one of the clones has complet
e identity with the mature enzyme sequence of the cysteine proteinase
papaya proteinase omega (PpOMEGA). The second clone contains ten indiv
idual bp changes compared with the first and encodes a protein with th
ree single-aa substitutions, only one of which is located in the matur
e sequence, but most noticeably carries an additional 19-aa C-terminal
extension. The clones encode pre-pro precursor isoforms of PpOMEGA. T
he former of these clones has been expressed in Escherichia coli using
a T7 polymerase expression system to produce insoluble pro-enzyme whi
ch has been solubilized and refolded to yield auto-activable pro-PpOME
GA.