Alpha-helical Coils Research Articles

Building with alphahelical coiled coils

Protein Design Understanding how proteins fold into well-defined three-dimensional structures has been a longstanding challenge. Increased understanding has led to increased success at designing proteins that mimic existing protein folds. This raises the possibility of custom design of proteins with structures not seen in nature. Thomson et al. describe the design of channelcontaining α-helical barrels, and Huang et al. designed hyperstable helical bundles. Both groups used rational and computational design to make new protein structures based on α-helical coiled coils but took different routes to reach different target structures. Science , this issue p. [485][1], p. [481][2] [1]: /lookup/doi/10.1126/science.1257452 [2]: /lookup/doi/10.1126/science.1257481

Molecular cloning and characterization of fox testis kinectin

Kinectin was isolated and characterized from a fox testis cDNA library using a monoclonal antibody (FTA-1) raised against testis surface proteins. The cDNA sequence of 4,479 nucleotides encodes an ORF of 1,330 amino acids (aa) with high homology to mouse, human, and chicken kinectins (GenBank Accession Number AF095786). Southern analysis was used to show that genes homologous to kinectin are present in several mammal species and in at least one marsupial, but not in bacteria. Alternatively spliced forms of fox kinectin were identified, and one of these is uniquely expressed in brain and spleen tissues. Kinectin expression was highest in testis relative to other tissues examined. Sequence analysis and comparisons between species revealed that kinectin encodes multiple alpha-helical coiled coils predicted to form dimers, and is, therefore, likely to exist as a dimer. The results presented in this article suggest that kinectin is required for spermatogenesis, but is not a likely candidate for use in immunocontraceptive vaccines.

Alpha-Helical Coiled Coil Trimerization Domain of Chicken Cartilage Matrix Protein (Oxidized)

Alpha-Helical Coiled Coil Trimerization Domain of Chicken Cartilage Matrix Protein (Oxidized)

Facile synthesis of block copolypeptides of defined architecture.

Many natural polymeric materials (particularly structural proteins) display a hierarchy of structure over several length scales. Block copolymers are able to self-assemble into ordered nanostructures, but the random-coiled nature of their polymer chains usually suppresses any further levels of organization. The use of components with regular structures, such as rigid-rod polymers, can increase the extent of spatial organization in self-assembling materials. But the synthesis of such polymeric components typically involves complicated reaction steps that are not suitable for large-scale production. Proteins form hierarchically organized structures in which the fundamental motifs are generally alpha-helical coils and beta-sheets. Attempts to synthesize polypeptides with well-defined amino-acid sequences, which might adopt similar organized structures, have been plagued by unwanted side reactions that give rise to products with a wide range of molecular weights, hampering the formation of well-defined peptide block copolymers. Here I describe a polymerization strategy that overcomes these difficulties by using organonickel initiators which suppress chain-transfer and termination side reactions. This approach allows the facile synthesis of block copolypeptides with well-defined sequences, which might provide new peptide-based biomaterials with potential applications in tissue engineering, drug delivery and biomimetic composite formation.

A trimeric, alpha-helical, coiled coil peptide: association stoichiometry and interaction strength by analytical ultracentrifugation.

Alpha-helical coiled coils are proving to be almost ideal systems for the modelling of peptide and protein self-association processes. Stable oligomeric systems, in which the stoichiometry is well defined, can be produced by the careful selection of the appropriate amino acid sequence, although the principles behind this are still not fully understood. Here we report on a 35 residue peptide, FZ, synthesized by the solid phase method, which was originally designed to form a dimer, but which, in fact, associates to the trimeric state. A detailed characterization of the associative properties of the peptide has been performed by circular dichroism spectroscopy and, in particular, by sedimentation equilibrium in the analytical ultracentrifuge. The presence of the trimeric state, which is stable even at low peptide concentrations, has been confirmed by various independent methods of analysis for molar mass. The effects of both temperature and of guanidinium chloride on the peptide have been investigated and both found to be peptide-concentration dependent. The unfolding induced by the denaturant cannot be adequately described by a simple, two state monomer-trimer equilibrium.

Dictyostelium discoideum myoJ: a member of a broadly defined myosin V class or a class XI unconventional myosin?

The simple eukaryote Dictyostelium discoideum contains at least 12 unconventional myosin genes. Here we report the characterization of one of these, myoJ, a gene initially identified through a physical mapping screen. The myoJ gene encodes a high molecular weight myosin, and analysis of the available deduced amino acid sequence reveals that it possesses six IQ motifs and sequences typical of alpha helical coiled coils in the tail region. Therefore, myoJ is predicted to exist as a dimer with up to 12 associated light chains (six per heavy chain). The 7.8 kb myoJ mRNA is expressed all throughout the life cycle of D. discoideum. The myoJ gene has been disrupted and a phenotypic analysis of the mutant cells initiated. Finally, phylogenetic analysis of the head region reveals that myoJ is most similar to two plant myosin genes, Arabidopsis MYA1 and MYA2, that have been alternatively suggested to be either members of the myosin V class or founding members of the myosin XI class.