K. Hagelin et al., INTERSPECIES CROSS-REACTIVITY OF A MONOCLONAL-ANTIBODY DIRECTED AGAINST WHEAT CHLOROPLAST FRUCTOSE-1,6-BISPHOSPHATASE, Cellular and molecular biology, 42(5), 1996, pp. 673-682
The primary structure of several chloroplast fructose-1,6-bisphosphata
se (CFBPase) was deduced from DNA sequences, but only spinach, pea and
rapeseed enzymes have been characterized structurally. We analyzed wh
ether CFBPases from different phylogenetic origin contain a common epi
tope. To this end a DNA fragment of 1200 base pairs encoding 338 amino
acid residues of wheat CFBPase (38 kDa) was cloned in the expression
plasmid pGEX-1 in frame with the gene coding for glutathione S-transfe
rase (GT) of Schistosoma japonicun (26.5 kDa). Upon transformation of
Escherichia coli and induction with isopropyl-beta-D-thiogalactopyrano
side, centrifugation of the lysate partitioned 10% of the fusion prote
in in the supernatant fraction and the remaining 90% in the precipitat
e. The expected 55 kDa protein was purified from both the soluble and
the particulate fraction by affinity chromatography on columns of glut
athione-agarose. This fusion protein was successfully used to produce
a monoclonal antibody that specifically recognized the CFBPase region
of the fusion protein but not the GT moiety. Moreover, the monoclonal
antibody immunoreacted not only with polypeptides (ca. 40 kDa) present
in leaf crude extracts of other varieties of wheat (Triticum spelta,
T. aestivum and T. durum), but also with homogeneous preparations of t
he spinach (Spinacia oleracea) and rapeseed (Brassica napus) enzymes.
Thus, the cross reaction of this monoclonal antibody with counterparts
from different plant species indicates the persistency of a common ep
itope through biological evolution.