Subcellular targeting of human interleukin-10 in plants

The utility of plants for the production of a wide range of recombinant proteins is now clearly established. However, the challenge remains to produce these proteins at sufficient concentrations for extraction to be economically feasible. In this paper, we have investigated the ability of plant cells to accumulate the human interleukin-10 (IL-10) protein targeted to chloroplasts and mitochondria. We found that IL-10 accumulates in chloroplasts only if a 6 x His tag is added at the C-terminus of the protein. The hexapeptide may provide protection from degradation. Conversely, the IL-10 protein does not accumulate in mitochondria. Analysis of the chloroplast-targeted IL-10 protein revealed only monomeric IL-10 and limited biological activity in in vitro cell assays.     

Immunogenicity of the capsid protein VP2 from porcine parvovirus expressed in low alkaloid transgenic tobacco

Porcine parvovirus is a widespread infectious viral disease with serious consequences to the reproductive health of swine. We have expressed the VP2 capsid protein of porcine parvovirus in the leaves of low alkaloid transgenic tobacco at approximately 0.3% of total soluble protein. Self-assembled virus-like particles were observed in planta by electron microscopy. Total soluble protein was extracted from the plant tissue and administered to mice by subcutaneous injection. An immune response was detected in these mice. The ability of serum antibodies to neutralize the infectivity of porcine parvovirus was further examined by a serum neutralization assay and was determined to be 1:2700–1:3900, a clear indication of the potential of VP2 expressed in plant material as a subunit vaccine against porcine parvovirus.     

Dolichol and polyprenol kinase activities in microsomes from etiolated rye seedlings.

Dolichol kinase activity in microsomes from etiolated rye seedlings had a pH optimum at 8 with a shoulder at pH 6.5. Triton X-100 (0.4%) was required for optimum activity. Exogenous divalent cations did not enhance activity, although Mg+2 was added routinely. Rye microsomes were found to contain dolichol and polyprenol in a ratio of 3 to 2. Rye, soybean embryo, and rat liver microsomes catalyzed the synthesis of 78, 52, and 516 nmol [14C]dolichyl phosphate/(mg microsomal protein.h) compared with 21, 22, and 49 nmol [3H]polyprenyl phosphate/(mg microsomal protein.h), respectively. It is clear that microsomes from plant systems can catalyze the phosphorylation of polyprenol better than rat liver when compared with their abilities to catalyze the phosphorylation of dolichol. It is not known whether one or more kinases is responsible for catalyzing the phosphorylation of these two closely related groups of compounds.