Protein kinase domain of twitchin has protein kinase activity and an autoinhibitory region

Twitchin is a 753-kDa polypeptide located in the muscle A-bands of the nematode, Caenorhabditis elegans. It consists of multiple copies of both fibronectin III and immunoglobulin C2 domains and, near the C terminus, a protein kinase domain with greatest homology to the catalytic domains of myosin light chain kinases. We have expressed and purified from Escherichia coli twitchin's protein kinase catalytic core and flanking sequences that do not include fibronectin III and immunoglobulin C2 domains. The protein was shown to phosphorylate a model substrate and to undergo autophosphorylation. The autophosphorylation occurs at a slow rate, attaining a maximum at 3 h with a stoichiometry of about 1.0 mol of phosphate/mol of protein, probably through an intramolecular mechanism. Sequence analysis of proteolytically derived phosphopeptides revealed that autophosphorylation occurred N-terminal to the catalytic core, predominantly at Thr-5910, with possible minor sites at Ser5912 and/or Ser-5913. This portion of twitchin (residues 5890-6268) was also phosphorylated in vitro by protein kinase C in the absence of calcium and phosphotidylserine, but not by cAMP-dependent protein kinase. By comparing the activities of three twitchin segments, the enzyme appears to be inhibited by the 60-amino acid residues lying just C-terminal to the kinase catalytic core. Thus, like a number of other protein kinases including myosin light chain kinases, the twitchin kinase appears to be autoregulated.

[A new species of Pseudomonas]

A strain No. 9191 isolated from fruit juice mineral drink is gram-negative short-rod. It differs from reported species of Pseudomonas in morphological, physiological and biochemical characteristics. Main characteristics of No. 9191 are single polar flagelled, oxidase and catalase positive, no acid from glucose but producing alkali, nitrate reduced to nitrite, inability to hydrolize gelatin and starch, arginine dihydrolase absent, no growth in presence of 0.85% NaCl. The G+C mol% of DNA is 65.15. It is named Pseudomonas halosensibilis Zou & Cai nov. sp. by the sensibility property for salt.

Effect of the mutation of tyrosine 713 in p93c-fes on its catalytic activity and ability to promote myeloid differentiation in K562 cells

The protooncogene protein-tyrosine kinase c-fes plays an active role in the induction of terminal myeloid differentiation in myeloid leukemia cells. Although p93c-fes contains two autophosphorylation sites, it is not known what role they play in its catalytic or biological activities. To address this question, the major autophosphorylation site at tyrosine 713 was mutated to phenylalanine (YF713), and the mutated cDNA was expressed in a baculovirus system to assess catalytic activity, as well as in an inducible retrovirus to determine its biological activity. The major phosphopeptide in p93c-fes in vitro contained Y713 and was absent in the YF713 mutant, which exhibited an 85% loss of autophosphorylation activity. The catalytic activity of p93c-fesYF713 with either RCM-lysozyme or poly(Glu,Tyr)4:1 as substrate was reduced by 85 and 78%, respectively, in comparison to p93c-fes. Retroviral infection of K562 cells with the c-fes cDNA under the control of the mouse metallothionein promoter increased superoxide formation, phagocytosis, CD13 and CD33 antigen expression, and doubling time 4-6 days after induction. Cells infected with c-fesYF713 exhibited 40% less superoxide formation but similar levels of phagocytosis, CD13/CD33 antigen, and doubling time in comparison to cells infected with c-fes. The level of phosphotyrosine-containing proteins did not markedly differ between K562 cells expressing either neo, c-fes, or c-fesYF713, with the exception of a reduction in the level of a 210-kDa protein specifically in both c-fes-expressing cell lines. The p210 was tentatively identified as bcr-abl, whose level was also reduced in cells expressing c-fes or c-fesYF713.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacological study on Cordyceps sinensis (Berk.) Sacc. and ze-e Cordyceps]

The Ze-e Cordyceps is similar to the Cordyceps sinensis in such pharmacological actions as calming, enduring hypoxia, dilating trachea, male sex hormone action, antiphlogistic and toxicity, etc. It is thus suggested that the Ze-e Cordyceps may be used place of the Cordyceps sinensis in clinical practice.

Acidic fibroblast growth factor in the developing rat embryo

Compared to basic fibroblast growth factor (bFGF), a widely distributed, broad spectrum mitogen and mesoderm inducer, acidic fibroblast growth factor (aFGF) is reported to have an essentially neural distribution and to be undetectable in the early embryo. In the present investigation, we used immunoblotting and immunochemistry to assess the cellular and tissue distributions of aFGF and bFGF in 11-20-d rat embryos. Immunoblotting of crude and heparin-bound embryo extracts revealed faint bands at the expected 17-18-kD and predominant bands at an apparent molecular mass of 26 to 28-kD (despite reducing conditions) using multiple specific antibodies for aFGF and bFGF. Pretreatment with 8 M urea yielded 18-20-kD aFGF and bFGF and some 24-26-kD bFGF. Immunoreactivity for both aFGF and bFGF was positive and similar in the cytoplasm, nuclei, and extracellular matrix of cells of neuroectodermal and mesodermal origin, while it was negative in endoderm-derived cells. The distribution of immunoreactive aFGF and bFGF also showed changes during development that were associated with the process of cellular and tissue differentiation. For example, intensity and extent of immunoreactivity for both peptides progressively increased in the middle layer of the spinal cord with increasing differentiation of the neural cells. The immunostaining patterns were very similar for aFGF and bFGF for each organ and at each stage. In conclusion, high molecular mass forms of immunoreactive aFGF and bFGF are present in the rat embryo. Acidic FGF and bFGF are both widely distributed in tissues of neuroectodermal and mesodermal origin, and their distribution was very similar.

Root factors stimulate 32 P uptake and plasmalemma ATPase activity in vesicular-arbuscular mycorrhizal fungus, Gigaspora margarita

Root-inducing (Ri) T-DNA transformed roots of carrot were used as the plant partner in a study of ³² P absorption and plasmalemma ATPase activity in the hyphae of the vesicular-arbuscular mycorrhizal fungus Gigaspora margarita Becker & Hall. Hyphae from germinating spores were grown in the presence or absence of root exudates and volatiles. In the presence of these root factors, ³² P isotope labelling occurred in hyphae, auxiliary cells and spores, while in the absence of these factors, the labelling only occurred in fungal spores. Similarly, ATPase activity appeared on the fungal plasmalemma only in the presence of root factors. The use of the ATPase inhibitor, diethylstilbestrol, demonstrated the importance of plasmalemma ATPase in the stimulation of hyphal growth of this obligately biotrophic fungus.

Ectomycorrhizal ability of genetically different homokaryotic and dikaryotic mycelia of Hebeloma cylindrosporum

Ectomycorrhizas were synthesized under axenic conditions between Pinus pinaster (Ait.) Sol. and different mycelial cultures of Hebeloma cylindrosporum Romagnesi. These included a wild dikaryon and four sib-homokaryons (one for each mating type) belonging to the progeny of this fruiting strain. The homokaryotic mycelia formed typical ectomyeorrhizas showing a morphology and an ultrastructural organization similar to that of ectomyeorrhizas obtained with the parental dikaryon. The ultrastructural localization of acid phosphatase activities was also comparable for homokaryotic and dikaryotic mycorrhizas. These results demonstrate that the ectomycorrhizal ability is not restricted to the dikaryotic state of fungal life-cycle since homokaryotic mycelia also formed typical and functional ectomyeorrhizas. The formation of normal mycorrhizas by homokaryotic mycelia confirms the usefulness of H. cylindrosporum as a model for genetical studies and improvement of ectomycorrhizal fungi by means of chromosomal genetics.

Ultrastructural localization of ATPase activity in the Pinus sylvestris/Laccaria laccata ectomycorrhizal association

Ultrastructural localization of the plasmalemmal ATPase activity has been studied in basidiomycete ectomycorrhizas synthesized between Pinus sylvestris L, and Laccaria laccata Scop, ex Fries. The cortical cells showed a strong plasmalemma-bound ATPase activity. The activity was also associated with the fungal plasmalemma in the external hyphae, sheath and Hartig net. The plasmalemmal ATPase activity disappeared in degenerating cortical cells. In the Hartig net, only the parts of the plasmalemma adjacent to other hyphae were active. When the Hartig net hyphae adjoined on one side a living cortical cell and, on the other side, a dead cortical cell, the ATPase activity of fungus plasmalemma was asymmetrically distributed. These observations are discussed in relation to the possible function of ATPase in ectomycorrhizas.