Shift of fibril‐forming ability of the designed α‐helical coiled‐coil peptides into the physiological pH region

Recently, we designed a short α‐helical fibril‐forming peptide (αFFP) that can form α‐helical nanofibrils at acid pH. The non‐physiological conditions of the fibril formation hamper biomedical application of αFFP. It was hypothesized that electrostatic repulsion between glutamic acid residues present at positions (g) of the αFFP coiled‐coil sequence prevent the fibrillogenesis at neutral pH, while their protonation below pH 5.5 triggers axial growth of the fibril. To test this hypothesis, we synthesized αFFPs where all glutamic acid residues were substituted by glutamines or serines. The electron microscopy study confirmed that the modified αFFPs form nanofibrils in a wider range of pH (2.5-11). Circular dichroism spectroscopy, sedimentation, diffusion and differential scanning calorimetry showed that the fibrils are α‐helical and have elongated and highly stable cooperative tertiary structures. This work leads to a better understanding of interactions that control the fibrillogenesis of the αFFPs and opens opportunities for their biomedical applicatio

Plasmodium falciparum merozoite surface protein 2: epitope mapping and fine specificity of human antibody response against non-polymorphic domains.

BACKGROUND: Two long synthetic peptides representing the dimorphic and constant C-terminal domains of the two allelic families of Plasmodium falciparum merozoite surface proteins 2 are considered promising malaria vaccine candidates. The aim of the current study is to characterize the immune response (epitope mapping) in naturally exposed individuals and relate immune responses to the risk of clinical malaria. METHODS: To optimize their construction, the fine specificity of human serum antibodies from donors of different age, sex and living in four distinct endemic regions was determined in ELISA by using overlapping 20 mer peptides covering the two domains. Immune purified antibodies were used in Western blot and immunofluorescence assay to recognize native parasite derivate proteins. RESULTS: Immunodominant epitopes were characterized, and their distribution was similar irrespective of geographic origin, age group and gender. Acquisition of a 3D7 family and constant region-specific immune response and antibody avidity maturation occur early in life while a longer period is needed for the corresponding FC27 family response. In addition, the antibody response to individual epitopes within the 3D7 family-specific region contributes to protection from malaria infection with different statistical weight. It is also illustrated that affinity-purified antibodies against the dimorphic or constant regions recognized homologous and heterologous parasites in immunofluorescence and homologous and heterologous MSP2 and other polypeptides in Western blot. CONCLUSION: Data from this current study may contribute to a development of MSP2 vaccine candidates based on conserved and dimorphic regions thus bypassing the complexity of vaccine development related to the polymorphism of full-length MSP2

Malaria vaccine: why is it taking so long?

International audienc

Long synthetic peptides for the production of vaccines and drugs: a technological platform coming of age.

Long synthetic peptides (LSPs) have a variety of important clinical uses as synthetic vaccines and drugs. Techniques for peptide synthesis were revolutionized in the 1960s and 1980s, after which efficient techniques for purification and characterization of the product were developed. These improved techniques allowed the stepwise synthesis of increasingly longer products at a faster rate, greater purity, and lower cost for clinical use. A synthetic peptide approach, coupled with bioinformatics analysis of genomes, can tremendously expand the search for clinically relevant products. In this Review, we discuss efforts to develop a malaria vaccine from LSPs, among other clinically directed work

Organization of designed nanofibrils assembled from alpha-helical peptides as determined by electron microscopy.

Self-assembling peptides present attractive platforms for engineering materials with controlled nanostructures. Recently, an alpha-helical fibril forming peptide (alphaFFP) was designed that self-assembles into nanofibrils at acid pH. Circular dichroism spectroscopy, electron-microscopy and x-ray fibre diffraction data showed that the most likely structure of alphaFFP fibrils is a five-stranded coiled coil rope. In the present study, scanning transmission electron microscopy (STEM) was used to improve our understanding of the alphaFFP fibril structure. The measurements of fibril mass per length suggest that there are ten alpha-helices in transverse sections of the fibrils. Based on the known data, it is proposed that a predominant fibrillar structure of alphaFFP is a dimer of alpha-helical five stranded protofilaments wrapped around a common axis. It is shown that these structures have an axial dimension of 58 +/- 16 nm and a width of 4 +/- 1 nm. A small number of thin fibrils is also observed in the negative stained preparation and STEM images. The thin fibrils may correspond to the single protofilament

Malaria vaccine development using synthetic peptides as a technical platform.

The review covers the development of synthetic peptides as vaccine candidates for Plasmodium falciparum- and Plasmodium vivax-induced malaria from its beginning up to date and the concomitant progress of solid phase peptide synthesis (SPPS) that enables the production of long peptides in a routine fashion. The review also stresses the development of other complementary tools and actions in order to achieve the long sought goal of an efficacious malaria vaccine

Heart-specific splice-variant of a human mitochondrial ribosomal protein (mRNA processing; tissue specific splicing)

It has been proposed that splice-variants of proteins involved in mitochondrial RNA processing and translation may be involved in the tissue specificity of mitochondrial DNA disease mutations (Fischel-Ghodsian, 1998. Mol. Genet. Metab. 65, 97-104). To identify and characterize the structural components of mitochondrial RNA processing and translation, the Mammalian Mitochondrial Ribosomal Consortium has been formed. The 338 amino acid (aa) residues long MRP-L5 was identified (O'Brien et al., 1999. J. Biol. Chem. 274, 36043-36051), and its transcript was screened for tissue specific splice-variants. Screening of the EST databases revealed a single putative splice-variant, due to the insertion of an exon consisting of 89 nucleotides prior to the last exon. Screening of multiple cDNA libraries revealed this inserted exon to be present only in heart tissue, in addition to the predominant MRP-L5 transcript. Sequencing of this region confirmed the EST sequence, and showed in the splice-variant a termination triplet at the beginning of the last exon. Thus the inserted exon replaces the coding sequence of the regular last exon, and creates a new 353 aa long protein (MRP-L5V1). Sequence analysis and 3D modeling reveal similarity between MRP-L5 and threonyl-t-RNA synthetases, and a likely RNA binding site within MRP-L5, with the C-terminus in proximity to the RNA binding site. Sequence analysis of MRP-L5V1 also suggests a likely transmembrane domain at the C-terminus. Thus it is possible that the MRP-L5V1 C-terminus could interfere with RNA binding and may have gained a transmembrane domain. Further studies will be required to elucidate the functional significance of MRP-L5V1