Wei JZ et al. (2003) Proc Natl Acad Sci U S A "Bacillus thuringiensis crystal proteins that target nematodes."

Aroian RV, Fang SC, Wong C, Wei JZ, Carta L, Hale K, Platzer E

[Proc Natl Acad Sci U S A, 2003]

Bacillus thuringiensis (Bt) crystal proteins are pore-forming toxins used as insecticides around the world. Previously, the extent to which these proteins might also target the invertebrate phylum Nematoda has been mostly ignored. We have expressed seven different crystal toxin proteins from two largely unstudied Bt crystal protein subfamilies. By assaying their toxicity on diverse free-living nematode species, we demonstrate that four of these crystal proteins are active against multiple nematode species and that each nematode species tested is susceptible to at least one toxin. We also demonstrate that a rat intestinal nematode is susceptible to some of the nematicidal crystal proteins, indicating these may hold promise in controlling vertebrate-parasitic nematodes. Toxicity in nematodes correlates with damage to the intestine, consistent with the mechanism of crystal toxin action in insects. Structure-function analyses indicate that one novel nematicidal crystal protein can be engineered to a small 43-kDa active core. These data demonstrate that at least two Bt crystal protein subfamilies contain nematicidal toxins.

Zhang F et al. (2016) PLoS Pathog "Bacillus thuringiensis Crystal Protein Cry6Aa Triggers Caenorhabditis elegans Necrosis Pathway Mediated by Aspartic Protease (ASP-1)."

Zhang F, Sun M, Ruan L, Ju S, Wan D, Cheng C, Deng Y, Wang F, Ye X, Hu Z, Zhou W, Shi J, Peng D, Lin J, Yu Z

[PLoS Pathog, 2016]

Cell death plays an important role in host-pathogen interactions. Crystal proteins (toxins) are essential components of Bacillus thuringiensis (Bt) biological pesticides because of their specific toxicity against insects and nematodes. However, the mode of action by which crystal toxins to induce cell death is not completely understood. Here we show that crystal toxin triggers cell death by necrosis signaling pathway using crystal toxin Cry6Aa-Caenorhabditis elegans toxin-host interaction system, which involves an increase in concentrations of cytoplasmic calcium, lysosomal lyses, uptake of propidium iodide, and burst of death fluorescence. We find that a deficiency in the necrosis pathway confers tolerance to Cry6Aa toxin. Intriguingly, the necrosis pathway is specifically triggered by Cry6Aa, not by Cry5Ba, whose amino acid sequence is different from that of Cry6Aa. Furthermore, Cry6Aa-induced necrosis pathway requires aspartic protease (ASP-1). In addition, ASP-1 protects Cry6Aa from over-degradation in C. elegans. This is the first demonstration that deficiency in necrosis pathway confers tolerance to Bt crystal protein, and that Cry6A triggers necrosis represents a newly added necrosis paradigm in the C. elegans. Understanding this model could lead to new strategies for nematode control.

Xu Y et al. (2013) Acta Crystallogr Sect F Struct Biol Cryst Commun "Purification, crystallization and preliminary crystallographic analysis of 3-hydroxyacyl-CoA dehydrogenase from Caenorhabditis elegans."

Xu Y, Sun F

[Acta Crystallogr Sect F Struct Biol Cryst Commun, 2013]

3-Hydroxyacyl-CoA dehydrogenase (HAD; EC 1.1.1.35) is the enzyme that catalyzes the third step in fatty-acid -oxidation, oxidizing the hydroxyl group of 3-hydroxyacyl-CoA to a keto group. The 3-hydroxyacyl-CoA dehydrogenase from Caenorhabditis elegans (cHAD) was cloned, overexpressed in Escherichia coli and purified to homogeneity for crystallography. Initial crystals were obtained by the hanging-drop vapour-diffusion method. Optimization of the precipitant concentration and the pH yielded two types of well diffracting crystals with parallelepiped and cuboid shapes, respectively. Complete diffraction data sets were collected and processed from both crystal types. Preliminary crystallographic analysis indicated that the parallelepiped-shaped crystal belonged to space group P1, while the cuboid-shaped crystal belonged to space group P212121. Analyses of computed Matthews coefficient and self-rotation functions suggested that there are two cHAD molecules in one asymmetric unit in both crystals, forming identical dimers but packing in distinct manners.

Luo H et al. (2013) Appl Microbiol Biotechnol "The effects of Bacillus thuringiensis Cry6A on the survival, growth, reproduction, locomotion, and behavioral response of Caenorhabditis elegans."

Xia L, Luo H, Zhou Q, Yu Z, Xiong J

[Appl Microbiol Biotechnol, 2013]

Several families of crystal proteins from Bacillus thuringiensis exhibit nematicidal activity. Cry5B protein, a pore-forming toxin, has been intensively studied yielding many insights into the mode of action of crystal protein at molecular level and pathogenesis of pore-forming toxins. However, little attention was paid to Cry6A, another representative nematicidal crystal protein. Cry6A shares very low homology with Cry5B at amino acid sequence and probably acts in a distinct pathway from Cry5B and even the other main commercial crystal proteins. In the current study, we comprehensively investigated the nematicidal properties of Cry6Aa2 against the free-living soil nematode Caenorhabditis elegans and examined the physical response of C. elegans to Cry6Aa2 attack. Our results indicate that Cry6Aa2 exhibits high lethal activity to C. elegans and could cause detrimental effects on C. elegans, including obviously suppressed growth, decreased brood size, and even abnormal motility. Meanwhile, our study additionally shows that C. elegans could defend against the Cry6Aa2 toxin harmful threat through behavioral defense responses, such as reduced oral uptake and physical avoidance. In general, this study suggests that Cry6Aa2 possesses diverse nematicidal properties, which strongly indicates that Cry6Aa2 is a promising potential candidate of nematicidal agent. Moreover, this study highlights the importance of behavioral responses in defense of C. elegans for survival and demonstrates the key role of crystal protein in the interaction of B. thuringiensis-C. elegans. These findings could shed light on understanding the interaction of C. elegans with B. thuringiensis and provide a perfect model to study the role of pathogenic factor in the interaction of pathogen-host.

Kamal M et al. (2024) Nat Commun "A rapid in vivo pipeline to identify small molecule inhibitors of amyloid aggregation."

Tiwari OS, Han D, Levy D, Knox J, Horne RI, Laor Bar-Yosef D, Gazit E, Roy PJ, Kamal M, Vendruscolo M, Burns AR

[Nat Commun, 2024]

Amyloids are associated with over 50 human diseases and have inspired significant effort to identify small molecule remedies. Here, we present an in vivo platform that efficiently yields small molecule inhibitors of amyloid formation. We previously identified small molecules that kill the nematode C. elegans by forming membrane-piercing crystals in the pharynx cuticle, which is rich in amyloid-like material. We show here that many of these molecules are known amyloid-binders whose crystal-formation in the pharynx can be blocked by amyloid-binding dyes. We asked whether this phenomenon could be exploited to identify molecules that interfere with the ability of amyloids to seed higher-order structures. We therefore screened 2560 compounds and found 85 crystal suppressors, 47% of which inhibit amyloid formation. This hit rate far exceeds other screening methodologies. Hence, in vivo screens for suppressors of crystal formation in C. elegans can efficiently reveal small molecules with amyloid-inhibiting potential.

Loo TW et al. (2013) Biochemistry "Drug rescue distinguishes between different structural models of human P-glycoprotein."

Loo TW, Clarke DM

[Biochemistry, 2013]

There is no high-resolution crystal structure of the human P-glycoprotein (P-gp) drug pump. Homology models of human P-gp based on the crystal structures of mouse or Caenorhabditis elegans P-gps show large differences in the orientation of transmembrane segment 5 (TM5). TM5 is one of the most important transmembrane segments involved in drug-substrate interactions. Drug rescue of P-gp processing mutants containing an arginine at each position in TM5 was used to identify positions facing the lipid or internal aqueous chamber. Only the model based on the C. elegans P-gp structure was compatible with the drug rescue results.

Symersky J et al. (2004) Acta Crystallogr D Biol Crystallogr "Structural genomics of Caenorhabditis elegans: structure of the BAG domain."

Schormann N, Luo M, Luan CH, Symersky J, Bunzel R, Zhang Y, Li S, Pruett P

[Acta Crystallogr D Biol Crystallogr, 2004]

Binding of the BAG domain to the eukaryotic chaperone heat-shock protein (Hsp70) promotes ATP-dependent release of the protein substrate from Hsp70. Although the murine and human BAG domains have been shown to form an antiparallel three-helix bundle, the Caenorhabditis elegans BAG domain is formed by two antiparallel helices, while the third helix is extended away and stabilized by crystal-packing interactions. A small beta-sheet between helices 2 and 3 interferes with formation of the intramolecular three-helix bundle. However, intermolecular three-helix bundles are observed throughout the crystal packing and suggest that stable functional dimers and tetramers can be formed in solution. The structure may represent a new folding type of the BAG domain.

Li S et al. (2002) J Biol Chem "Crystal structure of the cytoskeleton-associated protein glycine-rich (CAP-Gly) domain."

Thomas W, Carson M, Li S, DeLucas LJ, Luo M, Luan CH, Tsao J, Qiu SH, Wang BC, Zhao J, Sha B, Nagy LA, Chen H, Finley J, Liu ZJ, Johnson D, Lin G

[J Biol Chem, 2002]

Cytoskeleton-associated proteins (CAPs) are involved in the organization of microtubules and transportation of vesicles and organelles along the cytoskeletal network. A conserved motif, CAP-Gly, has been identified in a number of CAPs, including CLIP-170 and dynactins. The crystal structure of the CAP-Gly domain of Caenorhabditis elegans F53F4.3 protein, solved by single wavelength sulfur-anomalous phasing, revealed a novel protein fold containing three beta-sheets. The most conserved sequence, GKNDG, is located in two consecutive sharp turns on the surface, forming the entrance to a groove. Residues in the groove are highly conserved as measured from the information content of the aligned sequences. The C-terminal tail of another molecule in the crystal is bound in this groove.

Sleeman BD et al. (2024) Math Biosci "A theoretical model of anaphase."

Sleeman BD, Stewart IW

[Math Biosci, 2024]

This paper develops a theory for anaphase in cells. After a brief description of microtubules, the mitotic spindle and the centrosome, a mathematical model for anaphase is introduced and developed in the context of the cell cytoplasm and liquid crystalline structures. Prophase, prometaphase and metaphase are then briefly described in order to focus on anaphase, which is the main study of this paper. The entities involved are modelled in terms of liquid crystal defects and microtubules are represented as defect flux lines. The mathematical techniques employed make extensive use of energy considerations based on the work that was developed by Dafermos (1970) from the classical Frank-Oseen nematic liquid crystal energy (Frank, 1958; Oseen, 1933). With regard to liquid crystal theory we introduce the concept of regions of influence for defects which it is believed have important implications beyond the subject of this paper. The results of this paper align with observed biochemical phenomena and are explored in application to HeLa cells and Caenorhabditis elegans. This unified approach offers the possibility of gaining insight into various consequences of mitotic abnormalities which may result in Down syndrome, Hodgkin lymphoma, breast, prostate and various other types of cancer.

Lynagh T et al. (2011) J Biol Chem "Molecular determinants of ivermectin sensitivity at the glycine receptor chloride channel."

Lynch JW, Webb TI, Cromer BA, Dixon CL, Lynagh T

[J Biol Chem, 2011]

Ivermectin is an anthelmintic drug that works by activating glutamate-gated chloride channel receptors (GluClRs) in nematode parasites. GluClRs belong to the Cys-loop receptor family that also includes glycine receptor (GlyR) chloride channels. GluClRs and A288G mutant GlyRs are both activated by low nanomolar ivermectin concentrations. The crystal structure of the Caenorhabditis elegans GluClR complexed with ivermectin has recently been published. Here, we probed ivermectin sensitivity determinants on the 1 GlyR using site-directed mutagenesis and electrophysiology. Based on a mutagenesis screen of transmembrane residues, we identified Ala288 and Pro230 as crucial sensitivity determinants. A comparison of the actions of selamectin and ivermectin suggested the benzofuran C05-OH was required for high efficacy. When taken together with docking simulations, these results supported a GlyR ivermectin binding orientation similar to that seen in the GluClR crystal structure. However, whereas the crystal structure shows that ivermectin interacts with the GluClR via H-bonds with Leu218, Ser260, and Thr285 ( GluClR numbering), our data indicate that H-bonds with residues homologous to Ser260 and Thr285 are not important for high ivermectin sensitivity or direct agonist efficacy in A288G 1 GlyRs or three other GluClRs. Our data also suggest that van der Waals interactions between the ivermectin disaccharide and GlyR M2-M3 loop residues are unimportant for high ivermectin sensitivity. Thus, although our results corroborate the ivermectin binding orientation as revealed by the crystal structure, they demonstrate that some of the binding interactions revealed by this structure do not pertain to other highly ivermectin-sensitive Cys-loop receptors.