Analysis of the function of a hyperthermophilic endoglucanase from Pyrococcus horikoshii that hydrolyzes crystalline cellulose

A hyperthermophilic -1,4 endoglucanase was identified in Pyrococcus horikoshii, a hyperthermophilic archaeon. In order to clarify the function of the protein in detail, structural and catalytic site studies were performed using protein engineering. By removing some of the C-terminal sequence of the ORF of the endoglucanase (PH1171), two types of recombinant proteins were expressed from one ORF, using Escherichia coli. One exhibited endoglucanase activity, and the other did not. An SD-like sequence was identified in the ORF of the endoglucanase. By removing the SD-like sequence without changing the amino acid sequence of the endoglucanase, one recombinant endoglucanase was prepared effectively from E. coli. From the analysis of the N- and C-terminal regions of the ORF, this endoglucanase appears to be a secreted and membrane-binding enzyme of P. horikoshii. A mutation analysis of the endoglucanase, using the synthetic substrate, indicated that Glu342 is a candidate for the active center and plays a critical role in the activity of the enzyme. Additional catalytic amino acid residues were not found. These results indicate that the catalytic residue of the enzyme is different from that of typical family 5 endoglucanase, even though it has a high homology to the endoglucanase from Acidothermus celluloliticus. The activity of the enzyme, using carboxy methylcellulose and crystalline cellulose as the substrates, was increased, but not for a synthetic low-molecular substrate when a carbohydrate-binding module of chitinase from P. furiosus was added to the C-terminal region.     

Characterization and antifungal activity of gazyumaru (Ficus microcarpa) latex chitinases: both the chitin-binding and the antifungal activities of class I chitinase are reinforced with increasing ionic strength

Three chitinases, designated gazyumaru latex chitinase (GLx Chi)-A, -B, and -C, were purified from the latex of gazyumaru (Ficus microcarpa). GLx Chi-A,-B, and -C are an acidic class III (33 kDa, pI 4.0), a basic class I (32 kDa, pI 9.3), and a basic class II chitinase (27 kDa, pI > 10) respectively. GLx Chi-A did not exhibit any antifungal activity. At low ionic strength, GLx Chi-C exhibited strong antifungal activity, to a similar extent as GLx Chi-B. The antifungal activity of GLx Chi-C became weaker with increasing ionic strength, whereas that of GLx Chi-B became slightly stronger. GLx Chi-B and -C bound to the fungal cell-walls at low ionic strength, and then GLx Chi-C was dissociated from them by an escalation of ionic strength, but this was not the case for GLx Chi-B. The chitin-binding activity of GLx Chi-B was enhanced by increasing ionic strength. These results suggest that the chitin-binding domain of basic class I chitinase binds to the chitin in fungal cell walls by hydrophobic interaction and assists the antifungal action of the chitinase.     

Synthesis, absolute configuration, and application of enantiopure trans-1-aminobenz[f]indan-2-ol

Both novel enantiopure trans-1-aminobenz[f]indan-2-ols (4) were obtained from the racemate by the diastereomeric salt formation with (+)- and (-)-dibenzoyltartaric acids (8), respectively, and the absolute configuration of the enantiomer 4 in the less-soluble diastereomeric salt of racemic 4 with (+)-8 was determined to be (1S,2S) by an X-ray crystallographic analysis. The chiral recognition ability of the enantiopure amino alcohol was examined for the enantioseparation of racemic 2-arylalkanoic acids by the diastereomeric salt formation. The role of the naphthylene group of the amino alcohol was found to be closely associated with the stabilization of the crystal by CH/pi interactions on the basis of an X-ray crystallographic study.     

Regression of abdominal aortic aneurysm by inhibition of c-Jun N-terminal kinase

Abdominal aortic aneurysm (AAA) is a common disease among elderly people that, when surgical treatment is inapplicable, results in progressive expansion and rupture of the aorta with high mortality. Although nonsurgical treatment for AAA is much awaited, few options are available because its molecular pathogenesis remains elusive. Here, we identify JNK as a proximal signaling molecule in the pathogenesis of AAA. Human AAA tissue showed a high level of phosphorylated JNK. We show that JNK programs a gene expression pattern in different cell types that cooperatively enhances the degradation of the extracellular matrix while suppressing biosynthetic enzymes of the extracellular matrix. Selective inhibition of JNK in vivo not only prevented the development of AAA but also caused regression of established AAA in two mouse models. Thus, JNK promotes abnormal extracellular matrix metabolism in the tissue of AAA and may represent a therapeutic target.     

AtXTH27 plays an essential role in cell wall modification during the development of tracheary elements

Xyloglucan endotransglucosylases/hydrolases (XTHs) are a class of enzymes capable of catalyzing the molecular grafting between xyloglucans and/or the endotype hydrolysis of a xyloglucan molecule. They are encoded by 33 genes in Arabidopsis. Whereas recent studies have revealed temporally and spatially specific expression profiles for individual members of this family in plants, their biological roles are still to be clarified. To identify the role of each member of this gene family, we examined phenotypes of mutants in which each of the Arabidopsis XTH genes was disrupted. This was undertaken using a reverse genetic approach, and disclosed two loss-of-function mutants for the AtXTH27 gene, xth27-1 and xth27-2. These exhibited short-shaped tracheary elements in tertiary veins, and reduced the number of tertiary veins in the first leaf. In mature rosette leaves of the mutant, yellow lesion-mimic spots were also observed. Upon genetic complementation by introducing the wild-type XTH27 gene into xth27-1 mutant plants, the number of tertiary veins was restored, and the lesions disappeared completely. Extensive expression of the pXTH27::GUS fusion gene was observed in immature tracheary elements in the rosette leaves. The highest level of AtXTH27 mRNA expression in the rosette leaves was observed during leaf expansion, when the tracheary elements were elongating. These findings indicate that AtXTH27 plays an essential role during the generation of tracheary elements in the rosette leaves of Arabidopsis.     

Biological and biochemical characteristics of prion strains conserved in persistently infected cell cultures

Abnormal prion protein (PrP(Sc)) plays a central role in the transmission of prion diseases, but the molecular basis of prion strains with distinct biological characteristics remains to be elucidated. We analyzed the characteristics of prion disease by using mice inoculated with the Chandler and Fukuoka-1 strains propagated in a cultured mouse neuronal cell line, GT1-7, which is highly permissive to replication of the infectious agents. Strain-specific biological characteristics, including clinical manifestations, incubation period as related to the infectious unit, and pathological profiles, remained unchanged after passages in the cell cultures. We noted some differences in the biochemical aspects of PrP(Sc) between brain tissues and GT1-7 cells which were unlikely to affect the strain phenotypes. On the other hand, the proteinase K-resistant PrP core fragments derived from Fukuoka-1-infected tissues and cells were slightly larger than those from Chandler-infected versions. Moreover, Fukuoka-1 infection, but not Chandler infection, gave an extra fragment with a low molecular weight, approximately 13 kDa, in both brain tissues and GT1-7 cells. This cell culture model persistently infected with different strains will provide a new insight into the understanding of the molecular basis of prion diversity.     

Recent findings on genes associated with inflammatory disease

Inflammatory diseases encompass a variety of medical conditions. In this chapter, autoimmune diseases and allergic disorders will be our focus. The autoimmune diseases include organ-specific autoimmunities, such as type I diabetes mellitus and autoimmune thyroiditis (AITD), and organ non-specific disorders such as systemic lupus erythematosus (SLE). All of them seem to share aspects of aberrant immunologic tolerance toward self-antigens. Asthma and atopic diathesis are among the allergies. Crohn disease and SLE are relatively rare with a prevalence of 10-50 per 100,000, and rheumatoid arthritis (RA), psoriasis, AITD and asthma are commoner with a prevalence of 500 per 100,000 or much higher. The difference among ethnic groups is not prominent for rheumatoid arthritis, psoriasis, AITD or asthma, but Crohn disease and SLE affect some ethnic populations more than others. Although all of these disorders have some environmental component, asthma and atopy seem most affected by environmental factors, as is suggested by the significant increase in their incidence over the last several decades with changes in various environmental factors, especially in developed countries. Over the last 10 years, multiple linkage studies revealed many disease-linked loci throughout the genome with various consistencies. As implicated by some pathophysiological studies of inflammatory immune system related disorders, certain loci are involved in multiple disorders. In the following sections, reports on the identification of disease-associated genes or markers will be summarized for individual diseases (cytotoxic T lymphocyte-associated 4 (CTLA4), CARD15, DLG5, SLC22A4/A5, programmed cell death 1 (PDCD1), RUNX1, SLC9A3R1/NAT9, PADI4, ADAM33, DPP10, PHF11 and GPRA), followed by a discussion of the genes that have been implicated in multiple disorders.