Chanikarn Boonchoy. Investigation, cloning and expression of Alpha-MKN and Beta-MKN genes from Momordica Charantia L. locally cultivated in Thailand . Master's Degree(Biopharmaceutical Sciences). Mahidol University. : Mahidol University, 2004.
Investigation, cloning and expression of Alpha-MKN and Beta-MKN genes from Momordica Charantia L. locally cultivated in Thailand
Abstract:
Bitter melon or Mara Khee Nok (Momordica charantia L.), a common vegetable in
Thailand, has been used as a traditional medicine. Ribosome inactivating proteins (RIPs), a
group of proteins possessing some pharmacological activities e.g. anti-HIV and anti-cancer
properties, are found abundantly in this plant. The therapeutic potential with cloning and
expression of recombinant RIPs proteins could be investigated.
Alpha-momorcharin and MAP30 that are classified as type I RIPs, were isolated
from the seeds of M. charantia L. They possess similar structural and biological properties.
Both proteins contain basic glycoprotein with pI>8 and molecular weight of approximately
29-30 kDa. In this study, alpha-momorcharin and MAP30 related gene were cloned and
sequenced. The names of alpha-momorcharin and MAP30 related genes amplified from
Mara Khee Nok were designated as alpha-MKN and beta-MKN, respectively. The DNA
fragments containing alpha and beta-MKN genes were isolated and cloned into pGEM-T
Easy vector. Nucleotide sequences of alpha-MKN and beta-MKN were matched to the
sequence of alpha-momorcharin and MAP30 at 99.5% and 99% identities respectively.
Amino acid sequences alignment of alpha-MKN with alpha-momorcharin showed the two
mutated amino acid residues at position 53: F53Y and position 153: V153A. The beta-
MKN gene was subcloned into two expression vectors, pET32b and pET28a. The pET32b
vector was used to produce fusion beta-MKN protein which contained thioredoxin protein,
His•Tag, and enterokinase cleavage site fused to the N-terminus of beta-MKN protein. The
protein was called N-terminal fusion beta-MKN protein and the size was 49 kDa. The Nterminal
fusion beta-MKN protein was detected and purified by affinity chromatography.
The second vector, pET28a, was used to express beta-MKN protein, without fusion. Nterminal
fusion beta-MKN protein was produced at a higher level than beta-MKN protein.
The proteins, presumably similar to alpha-momorcharin and MAP30 from seeds of
M. charantia L., were collected and separated by ion-exchange chromatography. The
purified protein similar to alpha-momorcharin possessed anti-tumor activity against Human
epidermoid carcinoma of cavity (KB) and Breast cancer cell line (BC) showing the IC50 at
1.56 and 1.03 μg/ml, respectively, whereas the protein similar to MAP30 was effective only
to BC cell with IC50 at 4.56 μg/ml. Anti-HSV-1 activity was measured. The protein similar
to alpha-momorcharin was effective against HSV-1 with IC50 at 0.7 μg/ml.