Expression of schistosomal cathepsin L1 in Escherichia coli and evaluation of its protective capacity in an animal challenge

Schistosomes use proteinases to accomplish some tasks such as tissue penetration, tissue digestion for nutrition and evasion of host immune responses. The Cathepsin L is a cysteine proteinase of the papain superfamily detected in the gut lumen indicating that this enzyme contributes to the proteolysis of ingested hemoglobin. Due to these roles they play in the schistosome biology, proteolytic enzymes are considered potential targets to develop and direct anti-schistosomal therapies. In this work, the cDNA coding Cathepsin L1 of Schistosoma mansoni was cloned into the pAE vector that provides high-level expression of heterologous proteins in Escherichia coli. The recombinant protein was expressed as inclusion bodies, purified under denaturing conditions through nickel charged chromatography and used for experimental animal vaccination. ELISA was performed with the pooled sera. Although this protein showed to be immunogenic, mice immunized with three doses of recombinant protein plus aluminum hydroxide as adjuvant did not protect against S. mansoni infection.

Stability improvement of the fatty acid binding protein Sm14 from S. mansoni by Cys replacement Structural and functional characterization of a vaccine candidate

The Schistosoma mansoni fatty acid binding protein (FABP), Sm14, is a vaccine candidate against, S. mansoni and F. hepatica. Previously, we demonstrated the importance of a correct fold to achieve protection in immunized animals after cercariae challenge [[10]. C.R.R. Ramos, R.C.R. Figueredo, T.A. Pertinhez, M.M. Vilar, A.L.T.O. Nascimento, M. Tendler, I. Raw, A. Spisni, P.L. Ho, Gene structure and M20T polymorphism of the Schistosoma mansoni Sm14 fatty acid-binding protein: structural, functional and immunoprotection analysis. J. Biol. Chem. 278 (2003) 12745-12751.]. Here we show that the reduction of vaccine efficacy over time is due to protein dimerization and subsequent aggregation. We produced the mutants Sm14-M20(C62S) and Sm14-M20(C62V) that, as expected, did not dimerize in SDS-PAGE. Molecular dynamics calculations and unfolding experiments highlighted a higher structural stability of these mutants with respect to the wild-type. In addition, we found that the mutated proteins, after thermal denaturation, refolded to their active native molecular architecture as proved by the recovery of the fatty acid binding ability. Sm14-M20(C62V) turned out to be the more stable form over time, providing the basis to determine the first 3D solution structure of a Sm14 protein in its apo-form. Overall, Sm14-M20(C62V) possesses an improved structural stability over time, an essential feature to preserve its immunization capability and, in experimentally immunized animals, it exhibits a protection effect against S. mansoni cercariae infections comparable to the one obtained with the wild-type protein. These facts indicate this protein as a good lead molecule for large-scale production and for developing an effective Sm14 based anti-helminthes vaccine.

A mutation in human VAP-B--MSP domain, present in ALS patients, affects the interaction with other cellular proteins.

Amyotrophic Lateral Sclerosis (ALS) is the most common adult-onset Motor Neuron Disease (MND), characterized by motor neurons death in the cortex, brainstem and spinal cord. Ten loci linked to Familial ALS have been mapped. ALS8 is caused by a substitution of a proline by a serine in the Vesicle-Associated Membrane Protein-Associated protein-B/C (VAP-B/C). VAP-B belongs to a highly conserved family of proteins implicated in Endoplasmic Reticulum-Golgi and intra-Golgi transport and microtubules stabilization. Previous studies demonstrated that the P56S mutation disrupts the subcellular localization of VAP-B and that this position would be essential for Unfolded Protein Response (UPR) induced by VAP-B. In the present work we expressed and purified recombinant wild-type and P56S mutant VAP-B-MSP domain for the analysis of its interactions with other cellular proteins. Our findings suggest that the P56S mutation may lead to a less stable interaction of this endoplasmic reticulum protein with at least two other proteins: tubulin and GAPDH. These two proteins have been previously related to other forms of neurodegenerative diseases and are potential key points to understand ALS8 pathogenesis and other forms of MND. Understanding the role of these protein interactions may help the treatment of this devastating disease in the future.

A high-copy T7 Escherichia coli expression vector for the production of recombinant proteins with a minimal N-terminal His-tagged fusion peptide

We report here the construction of a vector derived from pET3-His and pRSET plasmids for the expression and purification of recombinant proteins in Escherichia coli based on T7 phage RNA polymerase. The resulting pAE plasmid combined the advantages of both vectors: small size (pRSET), expression of a short 6XHis tag at N-terminus (pET3-His) and a high copy number of plasmid (pRSET). The small size of the vector (2.8 kb) and the high copy number/cell (200-250 copies) facilitate the subcloning and sequencing procedures when compared to the pET system (pET3-His, 4.6 kb and 40-50 copies) and also result in high level expression of recombinant proteins (20 mg purified protein/liter of culture). In addition, the vector pAE enables the expression of a fusion protein with a minimal amino-terminal hexa-histidine affinity tag (a tag of 9 amino acids using XhoI restriction enzyme for the 5'cloning site) as in the case of pET3-His plasmid and in contrast to proteins expressed by pRSET plasmids (a tag of 36 amino acids using BamHI restriction enzyme for the 5'cloning site). Thus, although proteins expressed by pRSET plasmids also have a hexa-histidine tag, the fusion peptide is much longer and may represent a problem for some recombinant proteins.

A high-copy T7 Escherichia coli expression vector for the production of recombinant proteins with a minimal N-terminal His-tagged fusion peptide.

We report here the construction of a vector derived from pET3-His and pRSET plasmids for the expression and purification of recombinant proteins in Escherichia coli based on T7 phage RNA polymerase. The resulting pAE plasmid combined the advantages of both vectors: small size (pRSET), expression of a short 6XHis tag at N-terminus (pET3-His) and a high copy number of plasmid (pRSET). The small size of the vector (2.8 kb) and the high copy number/cell (200-250 copies) facilitate the subcloning and sequencing procedures when compared to the pET system (pET3-His, 4.6 kb and 40-50 copies) and also result in high level expression of recombinant proteins (20 mg purified protein/liter of culture). In addition, the vector pAE enables the expression of a fusion protein with a minimal amino-terminal hexa-histidine affinity tag (a tag of 9 amino acids using XhoI restriction enzyme for the 5'cloning site) as in the case of pET3-His plasmid and in contrast to proteins expressed by pRSET plasmids (a tag of 36 amino acids using BamHI restriction enzyme for the 5'cloning site). Thus, although proteins expressed by pRSET plasmids also have a hexa-histidine tag, the fusion peptide is much longer and may represent a problem for some recombinant proteins.