Resistance of soybean vegetative storage proteins (S-VSPs) to proteolysis by rumen microorganisms.
Soybean vegetative storage proteins (S-VSPs) are lysine-rich and, hence, are potentially of high nutritive value for high productive ruminants. Using S-VSPs from wild-type soybean and from transgenic tobacco plants expressing either one of the two S-VSPs subunits (S-VSP alpha or S-VSP beta) or both, we tested their stability in cow rumen fluid under in situ conditions, using SDS-polyacrylamide gel electrophoresis. Proteolysis and degradation pattern of S-VSPs from transgenic tobacco leaves occurred relatively fast compared with that of wild-type (WT) soybean plants. Comparing the two S-VSPs subunits expressed in transgenic plants, we found that S-VSP alpha was degraded much faster than S-VSP beta. The degradation pattern of S-VSPs in transgenic tobacco plants expressing both subunits resembled that of WT soybean. In contrast, the degradation pattern of transgenic tobacco plants expressing a single subunit was different. These finding suggest that the quaternary structure of S-VSPs may be an important factor determining their resistance to rumen degradation. Our results also suggest that the stability to rumen proteolysis of a given protein, when expressed in a transgenic plant, may not always be predictable and has to be verified.
Guenoune
Dana
D
Department of Agronomy and Natural Resources, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Landau
Serge
S
Amir
Rachel
R
Badani
Hana
H
Devash
Levana
L
Wolf
Shmuel
S
Galili
Shmuel
S
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D010450:Endopeptidases / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D007700:Kinetics; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011994:Recombinant Proteins / Q000378:metabolism; D012417:Rumen / Q000382:microbiology*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
D010940:Plant Proteins; D011994:Recombinant Proteins; C078148:VSPA protein, Glycine max; C078149:vspB protein, Glycine max; D010450:Endopeptidases