Dahl JL et al. (2011) J Bacteriol "Role of phase variation in the resistance of Myxococcus xanthus fruiting bodies to Caenorhabditis elegans predation."

Ulrich CH, Kroft TL, Dahl JL

[J Bacteriol, 2011]

The phenomenon of phase variation between yellow and tan forms of Myxococcus xanthus has been recognized for several decades, but it is not known what role this variation may play in the ecology of myxobacteria. We confirm an earlier report that tan variants are disproportionately more numerous in the resulting spore population of a M. xanthus fruiting body than the tan vegetative cells that contributed to fruiting body formation. However, we found that tan cells may not require yellow cells for fruiting body formation or starvation-induced sporulation of tan cells. Here we report three differences between the yellow and tan variants that may play important roles in the soil ecology of M. xanthus. Specifically, the yellow variant is more capable of forming biofilms, is more sensitive to lysozyme, and is more resistant to ingestion by bacteriophagous nematodes. We also show that the myxobacterial fruiting body is more resistant to predation by worms than are dispersed M. xanthus cells.

Dua A et al. (2024) Methods "Chromene-chromene Schiff base as a fluorescent chemosensor for Th4+ and its application in bioimaging of Caenorhabditis elegans."

Dua A, Goyal S, Sundararaj P, Thiruppathi G, Kumar Ramasamy S, Sharma HK, Saini P, Ashok Kumar SK, Selvam P

[Methods, 2024]

The manuscript presents the synthesis of a new di-chromene Schiff base (COM-CH) by combining 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide and 4-oxo-4H-chromene-3-carbaldehyde, and its characterization using various analytical techniques. The probe COM-CH functional group contains a hard donor atom that selectively complexes with Th⁴⁺ ions. This report investigated COM-CH's sensing ability towards Th⁴⁺ chromogenic and fluorogenic methods in ACN: H₂O (8:2, v/v) with Th⁴⁺ ions. The COM-CH-Th⁴⁺ complex was excited at 430 nm, resulting in a bright emission band at 475 nm with a 45 nm Stokes shift. The COM-CH probe demonstrated the highest performance at pH 4.0 to 8.0, with a sensitivity of 18.7 nM. The complex formation of COM-CH with Th⁴⁺ was investigated using NMR, FTIR spectrometry, and density functional theory. The COM-CH and Th⁴⁺ are bound with 2:1 stoichiometry and an association constant of 1.92 × 10⁸ M^-2. The probe's performance enabled the analysis of monazite sand and water samples for Th⁴⁺ content. The probe successfully detected Th⁴⁺ content in Caenorhabditis elegans, marking the first Th⁴⁺ detection in animal models.

Baker RH et al. (2012) Int J Parasitol "Melanisation of Teladorsagia circumcincta larvae exposed to sunlight: a role for GTP-cyclohydrolase in nematode survival."

Baker RH, Roberts B, Loer CM, Matthews JB, Britton C, Nisbet AJ

[Int J Parasitol, 2012]

Trichostrongylid nematode parasites of livestock inhabit two very different niches during their life-cycle; within the host and free-living in the environment. UV radiation plays a significant role in the survival of free-living, pre-parasitic nematode larvae, with different species exhibiting differing levels of sensitivity. In many eukaryotes, melanisation is a key protective mechanism against UV damage, however there is little information about this process in parasitic nematodes. Caenorhabditis elegans cat-4 mutants, which are deficient in the enzyme guanosine triphosphate-cyclohydrolase I (GTP-CH), have both depleted levels of melanin in their cuticles and an increased sensitivity to anthelmintic drugs. Some parasitic nematodes have very high levels of GTP-CH transcript in their pre-parasitic stages, suggesting an important role for this biopterin synthetic enzyme. Here, we show that the Tci-cat-4 gene, which encodes GTP-CH in Teladorsagia circumcincta, has a role in melanisation and is also capable of rescuing C. elegans cat-4 mutants. In addition, following exposure of T. circumcincta L3s to sunlight, there is a 32% increase in GTP-CH enzyme activity (P=0.019), and a 21% increase in levels of melanin (P=0.031) compared with unexposed larvae. These data suggest that one explanation for the high level of GTP-CH present in pre-parasitic stages of trichostrongylid nematodes is to facilitate melanisation in response to UV exposure.

Wierzchowski J et al. (2007) Nucleosides Nucleotides Nucleic Acids "Kinetics of C. elegans DcpS cap hydrolysis studied by fluorescence spectroscopy."

Davis RE, Jankowska-Anyszka M, Pietrzak M, Wierzchowski J, Darzynkiewicz E, Jemielity J, Kalek M, Bojarska E, Stepinski J

[Nucleosides Nucleotides Nucleic Acids, 2007]

DcpS (scavenger decapping enzyme) from nematode C. elegans readily hydrolyzes both monomethyl- and trimethylguanosine cap analogues. The reaction was followed fluorimetrically. The marked increase of fluorescence intensity after the cleavage of pyrophosphate bond in dinucleotides was used to determine K(m) and V(max)values. Kinetic parameters were similar for both classes of substrates and only slightly dependent on pH. The hydrolysis was strongly inhibited by methylene cap analogues (m(7)Gp(CH(2))ppG and m(7)Gpp(CH(2))pG) and less potently by ARCA (m(7,3'' O)GpppG).

Radoff DT et al. (2014) Elife "The accessory helix of complexin functions by stabilizing central helix secondary structure."

Dittman JS, Bai J, Snead D, Eliezer D, Radoff DT, Dong Y

[Elife, 2014]

The presynaptic protein complexin (CPX) is a critical regulator of synaptic vesicle fusion, but the mechanisms underlying its regulatory effects are not well understood. Its highly conserved central helix (CH) directly binds the ternary SNARE complex and is required for all known CPX functions. The adjacent accessory helix (AH) is not conserved despite also playing an important role in CPX function, and numerous models for its mechanism have been proposed. We examined the impact of AH mutations and chimeras on CPX function in vivo and in vitro using C. elegans. The mouse AH fully restored function when substituted into worm CPX suggesting its mechanism is evolutionarily conserved. CPX inhibitory function was impaired when helix propagation into the CH was disrupted whereas replacing the AH with a non-native helical sequence restored CPX function. We propose that the AH operates by stabilizing CH secondary structure rather than through protein or lipid interactions.

Arata Y et al. (2001) J Biol Chem "Sugar binding properties of the two lectin domains of the tandem repeat-type galectin LEC-1 (N32) of Caenorhabditis elegans. Detailed analysis by an improved frontal affinity chromatography method."

Kasai K-I, Arata Y, Hirabayashi J

[J Biol Chem, 2001]

The 32-kDa galectin (LEC-1 or N32) of the nematode Caenorhabditis elegans is the first example of a tandem repeat-type galectin and is composed of two domains, each of which is homologous to typical vertebrate 14-kDa-type galectins. To elucidate the biological meaning of this unique structure containing two probable sugar binding sites in one molecule, we analyzed in detail the sugar binding properties of the two domains by using a newly improved frontal affinity chromatography system. The whole molecule (LEC-1), the N-terminal lectin domain (Nh), and the C-terminal lectin domain (Ch) were expressed in Escherichia coli, purified, and immobilized on HiTrap gel agarose columns, and the extent of retardation of various sugars by the columns was measured. To raise the sensitivity of the system, we used 35 different fluorescence-labeled oligosaccharides (pyridylaminated (PA) sugars). All immobilized proteins showed affinity for N-acetyllactosamine-containing N-linked complex-type sugar chains, and the binding was stronger for more branched sugars. Ch showed 2-5-fold stronger binding toward all complex-type sugars compared with Nh. Both Nh and Ch preferred Galbeta1-3GlcNAc to Galbeta1-4GlcNAc. Because the Fucalpha1-2Galbeta1-3GlcNAc (H antigen) structure was found to interact with all immobilized protein columns significantly, the K(d) value of pentasaccharide Fucalpha1-2Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc-PA for each column was determined by analyzing the concentration dependence. Obtained values for immobilized LEC-1, Nh, and Ch were 6.0 x 10(-5), 1.3 x 10(-4), and 6.5 x 10(-5) m, respectively. The most significant difference between Nh and Ch was in their affinity for GalNAcalpha1-3(Fucalpha1-2)Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc-PA, which contains the blood group A antigen; the K(d) value for immobilized Nh was 4.8 x 10(-5) m, and that for Ch was 8.1 x 10(-4) m. The present results clearly indicate that the two sugar binding sites of LEC-1 have different sugar binding properties.

Gong T et al. (2018) EMBO J "PTRN-1/CAMSAP promotes CYK-1/formin-dependent actin polymerization during endocytic recycling."

Gong T, Zhou X, Yan Y, Gao J, Shi A, Chen J, Zhang J, Liu S, Liu H

[EMBO J, 2018]

Cargo sorting and membrane carrier initiation in recycling endosomes require appropriately coordinated actin dynamics. However, the mechanism underlying the regulation of actin organization during recycling transport remains elusive. Here we report that the loss of PTRN-1/CAMSAP stalled actin exchange and diminished the cytosolic actin structures. Furthermore, we found that PTRN-1 is required for the recycling of clathrin-independent cargo hTAC-GFP The N-terminal calponin homology (CH) domain and central coiled-coils (CC) region of PTRN-1 can synergistically sustain the flow of hTAC-GFP We identified CYK-1/formin as a binding partner of PTRN-1. The N-terminal GTPase-binding domain (GBD) of CYK-1 serves as the binding interface for the PTRN-1 CH domain. The presence of the PTRN-1 CH domain promoted CYK-1-mediated actin polymerization, which suggests that the PTRN-1-CH:CYK-1-GBD interaction efficiently relieves autoinhibitory interactions within CYK-1. As expected, the overexpression of the CYK-1 formin homology domain 2 (FH2) substantially restored actin structures and partially suppressed the hTAC-GFP overaccumulation phenotype in<i>ptrn-1</i>mutants. We conclude that the PTRN-1 CH domain is required to stimulate CYK-1 to facilitate actin dynamics during endocytic recycling.

Berry CL et al. (2012) Can J Microbiol "Chemical and biological characterization of sclerosin, an antifungal lipopeptide."

Brassinga AK, Loewen PC, Fernando WG, Donald LJ, de Kievit TR, Berry CL

[Can J Microbiol, 2012]

Pseudomonas sp. strain DF41 produces a lipopeptide, called sclerosin that inhibits the fungal pathogen Sclerotinia sclerotiorum . The aim of the current study was to deduce the chemical structure of this lipopeptide and further characterize its bioactivity. Mass spectrometry analysis determined the structure of sclerosin to be CH(3)-(CH(2))(6)-CH(OH)-CH(2)-CO-Dhb-Pro-Ala-Leu/Ile-Ala-Val-Val-Dhb-Thr-Val-Leu/Ile-Dhp-Ala-Ala-Ala-Val-Dhb-Dhb-Ala-Dab-Ser-Val-OH, similar to corpeptins A and B of the tolaasin group, differing by only 3 amino acids in the peptide chain. Subjecting sclerosin to various ring opening procedures revealed no new ions, suggesting that this molecule is linear. As such, sclerosin represents a new member of the tolaasin lipopeptide group. Incubation of S.sclerotinia ascospores and sclerotia in the presence of sclerosin inhibited the germination of both cell types. Sclerosin also exhibited antimicrobial activity against Bacillus species. Conversely, this lipopeptide demonstrated no zoosporicidal activity against the oomycete pathogen Phytophthora infestans . Next, we assessed the effect of DF41 and a lipopeptide-deficient mutant on the growth and development of Caenorhabditis elegans larvae. We discovered that sclerosin did not protect DF41 from ingestion by and degradation in the C.elegans digestive tract. However, another metabolite produced by this bacterium appeared to shorten the life-span of the nematode compared to C.elegans growing on Escherichia coli OP50.

Arata Y et al. (1997) J Biochem "The two lectin domains of the tandem-repeat 32-kDa galectin of the nematode Caenorhabditis elegans have different binding properties. Studies with recombinant protein."

Hirabayashi J, Kasai K-I, Arata Y

[J Biochem, 1997]

Some properties of recombinant proteins derived from the 32-kDa galectin isolated from the nematode Caenorhabditis elegans, which lectin is composed of two tandemly repeated homologous domains [Hirabayashi et al. (1992) J. Biol. Chem. 267, 15485], were studied in order to elucidate the function of this unique polypeptide architecture. We expressed the whole molecule (N32), the N-terminal lectin domain (Nh), and the C-terminal lectin domain (Ch) in Escherichia coli using the expression vector pET21a. All of the recombinant proteins were bound by asialofetuin-Sepharose. CD spectra of the recombinant proteins indicated all of them to be rich in beta-structure and properly refolded. Gel filtration on an HPLC column suggested that all of them existed as monomers. Neither Nh nor Ch seemed to form dimers, in contrast to vertebrate proto-type galectins. Only N32 showed hemagglutination activity towards trypsinized rabbit erythrocytes. Comparison of the affinity of N32, Nh, and Ch for asialofetuin-Sepharose by frontal affinity chromatography [Kasai et al. (1986) J. Chromatogr. 376, 33] showed that Ch has 7-fold weaker affinity than N32, and Nh proved to have still weaker affinity. Since the Asn residue in the CRD (carbohydrate recognition domain), which is conserved in all other galectins, is substituted by Ser in the case of Nh, these data suggest that the two CRDs in this tandem-repeat galectin have different sugar binding properties and that the 32-kDa galectin may serve as a heterobifunctional crosslinker.

Guan L et al. (2016) PLoS Genet "The Calponin Family Member CHDP-1 Interacts with Rac/CED-10 to Promote Cell Protrusions."

Liu JJ, Wang Y, Guan L, Ma X, Ding M, Zhang J

[PLoS Genet, 2016]

Eukaryotic cells extend a variety of surface protrusions to direct cell motility. Formation of protrusions is mediated by coordinated actions between the plasma membrane and the underlying actin cytoskeleton. Here, we found that the single calponin homology (CH) domain-containing protein CHDP-1 induces the formation of cell protrusions in C. elegans. CHDP-1 is anchored to the cortex through its amphipathic helix. CHDP-1 associates through its CH domain with the small GTPase Rac1/CED-10, which is a key regulator of the actin cytoskeleton. CHDP-1 preferentially binds to the GTP-bound active form of the CED-10 protein and preserves the membrane localization of GTP-CED-10. Hence, by coupling membrane expansion to Rac1-mediated actin dynamics, CHDP-1 promotes the formation of cellular protrusions in vivo.