Solution NMR studies of the plant peptide hormone CEP inform function.

The C-terminally Encoded Peptide (CEP) family of regulatory peptides controls root development in vascular plants. Here, we present the first NMR structures of CEP. We show that root-knot nematode (RKN: Meloidogyne spp.) also encodes CEP, presumably to mimic plant CEP as part of their stereotypic, parasitic interaction with vascular plants. Molecular dynamics simulations of plant- and nematode-encoded CEP displaying known posttranslational modifications (PTM) provided insight into the structural effects of PTM and the conformational plasticity and rigidity of CEP. Potential mechanisms of action are discussed with respect to the structure and sampling of conformational space.

A novel candidate vaccine for cytauxzoonosis inferred from comparative apicomplexan genomics.

Cytauxzoonosis is an emerging infectious disease of domestic cats (Felis catus) caused by the apicomplexan protozoan parasite Cytauxzoon felis. The growing epidemic, with its high morbidity and mortality points to the need for a protective vaccine against cytauxzoonosis. Unfortunately, the causative agent has yet to be cultured continuously in vitro, rendering traditional vaccine development approaches beyond reach. Here we report the use of comparative genomics to computationally and experimentally interpret the C. felis genome to identify a novel candidate vaccine antigen for cytauxzoonosis. As a starting point we sequenced, assembled, and annotated the C. felis genome and the proteins it encodes. Whole genome alignment revealed considerable conserved synteny with other apicomplexans. In particular, alignments with the bovine parasite Theileria parva revealed that a C. felis gene, cf76, is syntenic to p67 (the leading vaccine candidate for bovine theileriosis), despite a lack of significant sequence similarity. Recombinant subdomains of cf76 were challenged with survivor-cat antiserum and found to be highly seroreactive. Comparison of eleven geographically diverse samples from the south-central and southeastern USA demonstrated 91-100% amino acid sequence identity across cf76, including a high level of conservation in an immunogenic 226 amino acid (24 kDa) carboxyl terminal domain. Using in situ hybridization, transcription of cf76 was documented in the schizogenous stage of parasite replication, the life stage that is believed to be the most important for development of a protective immune response. Collectively, these data point to identification of the first potential vaccine candidate antigen for cytauxzoonosis. Further, our bioinformatic approach emphasizes the use of comparative genomics as an accelerated path to developing vaccines against experimentally intractable pathogens.

Divergent evolution of arrested development in the dauer stage of Caenorhabditis elegans and the infective stage of Heterodera glycines.

BACKGROUND: The soybean cyst nematode Heterodera glycines is the most important parasite in soybean production worldwide. A comprehensive analysis of large-scale gene expression changes throughout the development of plant-parasitic nematodes has been lacking to date. RESULTS: We report an extensive genomic analysis of H. glycines, beginning with the generation of 20,100 expressed sequence tags (ESTs). In-depth analysis of these ESTs plus approximately 1,900 previously published sequences predicted 6,860 unique H. glycines genes and allowed a classification by function using InterProScan. Expression profiling of all 6,860 genes throughout the H. glycines life cycle was undertaken using the Affymetrix Soybean Genome Array GeneChip. Our data sets and results represent a comprehensive resource for molecular studies of H. glycines. Demonstrating the power of this resource, we were able to address whether arrested development in the Caenorhabditis elegans dauer larva and the H. glycines infective second-stage juvenile (J2) exhibits shared gene expression profiles. We determined that the gene expression profiles associated with the C. elegans dauer pathway are not uniformly conserved in H. glycines and that the expression profiles of genes for metabolic enzymes of C. elegans dauer larvae and H. glycines infective J2 are dissimilar. CONCLUSION: Our results indicate that hallmark gene expression patterns and metabolism features are not shared in the developmentally arrested life stages of C. elegans and H. glycines, suggesting that developmental arrest in these two nematode species has undergone more divergent evolution than previously thought and pointing to the need for detailed genomic analyses of individual parasite species.