Febs Letters

doi: 10.1016/S0014-5793(04)00944-5pmid: N/A

doi: 10.1016/S0014-5793(04)00939-1pmid: N/A

Schatz, Gottfried

doi: 10.1016/j.febslet.2004.07.028pmid: 15304313

Brandazza, Anna; Angeli, Sergio; Tegoni, Mariella; Cambillau, Christian; Pelosi, Paolo

doi: 10.1016/j.febslet.2004.07.003pmid: 15304314

Thaumatin‐like proteins (TLPs) are polypeptides of about 200 residues synthesized by plants in response to fungal infection. In addition to the exceptionally strong sweet taste exhibited by some members, they are also reported to be endowed with endo‐β‐1,3‐glucanase activity and α‐amylase inhibiting properties. However, the detailed mechanism of their antifungal action is not completely understood. So far, TLPs have only been described in plants, with several members of the family expressed in the same species. Here, for the first time in animals, we report the identification of two genes encoding members of the thaumatin‐like proteins family in the desert locust Schistocerca gregaria and show their expression in different parts of the body. Southern blot and Western blot experiments revealed the presence of orthologous genes and their expression products in the related species Locusta migratoria. A search through the available genomes yielded similar sequences in the nematode Caenorhabditis but not in Drosophila and other insects. A three‐dimensional model of S. gregaria TLP suggests a glucanase function. As in plants, TLPs could play a defense role in insects against pathogens.

Salomon, Michael; Lempert, Ulrika; Rüdiger, Wolfhart

doi: 10.1016/j.febslet.2004.06.081pmid: 15304315

Phototropin is a membrane‐bound UV‐A/blue light photoreceptor of plants responsible for phototropism, chloroplast migration and stomatal opening. Characteristic are two LOV domains, each binding one flavin mononucleotide, in the N‐terminal half and having a serine/threonine kinase domain in the C‐terminal half of the molecule. We purified the N‐terminal half of oat phototropin 1, containing LOV1 and LOV2 domains, as a soluble fusion protein with the calmodulin binding peptide (CBP) by expression in Escherichia coli. Gel chromatography showed that it was dimeric in solution. While the fusion protein CBP‐LOV2 was exclusively monomeric in solution, the fusion protein CBP‐LOV1 occurred as monomer and dimer. The proportion of dimer increased on prolonged incubation. We conclude that native phototropin is a dimer and that the LOV1 domain is probably responsible for dimerization.

Laulagnier, Karine; Grand, David; Dujardin, Arnaud; Hamdi, Safouane; Vincent-Schneider, Hélène; Lankar, Danielle; Salles, Jean-Pierre; Bonnerot, Christian; Perret, Bertrand; Record, Michel

doi: 10.1016/j.febslet.2004.06.082pmid: 15304316

Aphasizhev, Ruslan; Aphasizheva, Inna; Simpson, Larry

doi: 10.1016/j.febslet.2004.07.004pmid: 15304317

The transferase activities that add uridylyl residues to RNA have been reported in several unicellular and metazoan organisms. Thus far, the two terminal uridylyltransferases (TUTases) involved in uridine insertion/deletion mRNA editing in mitochondria of trypanosomes were the only known enzymes with confirmed UTP specificity. Here, we demonstrate that protein sequences of editing TUTases may be used to predict novel UTP‐specific enzymes by data mining. The highest‐scoring open reading frame from Trypanosoma brucei was expressed and recombinant protein purified. This enzyme catalyzes a processive UMP incorporation and is not localized to the mitochondria suggesting a non‐editing biological function.

Manteca, Angel; Kamphausen, Thilo; Fanghanel, Jorg; Fischer, Gunter; Sanchez, Jesus

doi: 10.1016/j.febslet.2004.06.091pmid: 15304318

Cyclophilins are folding helper enzymes and represent a family of the enzyme class of peptidyl‐prolyl cis–trans isomerases. Here, we report the molecular cloning and biochemical characterization of SanCyp18, an 18‐kDa cyclophilin from Streptomyces antibioticus ATCC11891 located in the cytoplasm and constitutively expressed during development. Amino acid sequence analysis revealed a much higher homology to cyclophilins from Gram negative bacteria than to known cyclophilins from Streptomyces or other Gram positive bacteria. SanCyp18 is inhibited weakly by CsA, with a K i value of 21 μM, similar to cyclophilins from Gram negative bacteria. However, this value is more than 20‐fold higher than the K i values reported for cyclophilins from other Gram positive bacteria, which makes SanCyp18 unique within this group. The presence of SanCyp18 in Streptomyces is likely due to horizontal gene transmission from Gram‐negative bacteria to Streptomyces.

Sakamoto, Atsushi; Sakurao, Sho-hei; Fukunaga, Keiko; Matsubara, Toshiyuki; Ueda-Hashimoto, Manami; Tsukamoto, Shigefumi; Takahashi, Misa; Morikawa, Hiromichi

doi: 10.1016/j.febslet.2004.07.005pmid: 15304319

All plants examined to date possess non‐symbiotic hemoglobin whose physiological role remains unclear. The present study explored the catalytic function of three representative classes of the plant hemoglobin from Arabidopsis thaliana: AtGLB1, AtGLB2, and AtGLB3. Purified recombinant proteins of these hemoglobins displayed hydrogen peroxide‐dependent oxidation of several peroxidase substrates that was sensitive to cyanide, revealing intrinsic peroxidase‐like activity. In the presence of nitrite and hydrogen peroxide, AtGLB1 was the most efficient at mediating tyrosine nitration of its own and other proteins via the formation of reactive nitrogen species as a result of nitrite oxidation. AtGLB1 mRNA significantly accumulated in Arabidopsis seedlings exposed to nitrite, supporting the physiological relevance of its function to nitrite and nitrite‐derived reactive nitrogen species.

Boyault, Sandrine; Bianchi, Arnaud; Moulin, David; Morin, Sylvie; Francois, Mathias; Netter, Patrick; Terlain, Bernard; Bordji, Karim

doi: 10.1016/j.febslet.2004.06.090pmid: 15304320

Peroxisome proliferator‐activated receptor γ (PPARγ) ligands have been shown to inhibit the effects of proinflammatory cytokines such as interleukin‐1β (IL‐1β). This cytokine plays a key role in articular pathophysiologies by inducing the production of inflammatory mediators such as nitric oxide (NO) and prostaglandin E2 (PGE2). We previously demonstrated that 15d‐PGJ2 was more potent than troglitazone to counteract IL‐1β effects on chondrocytes. Here, we studied the action of 15d‐PGJ2 on intracellular targets in nuclear factor‐κB (NF‐κB) signalling pathway in IL‐1β treated rat chondrocytes. We found that 15d‐PGJ2 decreased inhibitor κBα (IκBα) degradation but not its phosphorylation by specifically inhibiting IκB kinase β (IKKβ), but not IKKα, enzymatic activity. We further evaluated the involvement of PPARγ in the anti‐inflammatory action of its ligands. In chondrocytes overexpressing functional PPARγ protein, 15d‐PGJ2 pre‐treatment inhibited inducible NO synthase and COX‐2 mRNA expression, nitrite and PGE2 production, p65 translocation and NF‐κB activation. Troglitazone or rosiglitazone pre‐treatment had no effect. 15d‐PGJ2 exhibited the same effect in chondrocytes overexpressing mutated PPARγ protein. These results suggest that 15d‐PGJ2 exerts its anti‐inflammatory effect in rat chondrocytes by a PPARγ‐independent mechanism, which can be conferred to a partial inhibition of IκBα degradation.