Crystal and molecular structure of a collagen-like polypeptide (Pro-Pro-Gly)10

(Pro-Pro-Gly)₁₀ forms single crystals, providing X-ray diffraction data to 0.22 nm resolution. In the crystals, the polypeptides form triplexes that aggregate end-to-end in quasi-infinite helices with axial translation per tripeptide h = 0.287 nm and the corresponding rotation t = ?102.9 °. The structure, which may be an allomorph of collagen, has been refined by the linked-atom least-squares procedure. In addition, three water molecules per tripeptide have been detected by Fourier difference syntheses. One of them forms an intrachain hydrogen-bonded bridge O(Pro₂) - - - W - - - O(Gly). There are also interchain hydrogen bonds (Gly)NH - - - O(Pro₁) within the triplex.     

Stereochemistry of leukotriene C-1

Leukotriene C-1, a “Slow Reacting Substance” (SRS), has been shown to possess the molecular Structure depicted by V (5(S)-hydroxy-6(R)-$\text{S}$-glutathionyl-7,9-$\text{trans}$-11,14-$\text{cis}$-eicosatetraenoic acid) by its identity with a totally synthetic product of known structure and stereochemistry.     

Gene Expression Profiling of Coccolith-Bearing Cells and Naked Cells in Haptophyte <Emphasis Type="Italic">Pleurochrysis haptonemofera</Emphasis> with a cDNA Macroarray System

Pleurochrysis haptonemofera is a unicellular marine coccolithophorid that has calcified scales, coccoliths, on the cell surface. Some coccolithophorids including P. haptonemofera have a coccolith-bearing stage and a naked stage in their life cycles. To characterize genes involved in the coccolithogenesis, we generated a total of 9550 expressed sequence tags (EST) from a normalized cDNA library that was prepared using both coccolith-bearing cells (C-cells) and naked cells (N-cells), constructed a cDNA macroarray using the EST clones, and then analyzed the gene expression specificity in C-cells and N-cells. When cDNA clones whose expression ratio exceeded 3-fold were selected, as many as 180 clones were identified as C-cell-specific ones, while only 12 were found to be N-cell-specific ones. These clones were sequenced, assembled, and homology-searched against a public nonredundant protein database. As a result, they were grouped into 54 C-cell-specific and 6 N-cell-specific genes, and 59% and 50% of these genes exhibited significant similarity to those of other known proteins, respectively. To assess mRNA expression further, Northern hybridization was performed for 12 of the C-cell-specific genes and one of the N-cell-specific ones. These clones, together with the new cDNA macroarray, will provide a powerful tool for the future genome-wide functional analysis of uncharacterized genes related to the regulation of the calcification and life cycle of coccolithophorids. Shoko Fujiwara and Yasutaka Hirokawa contributed equally to this work.     

Cloning and characterization of VIGG,a novel virus-induced grapevine protein,correlated with fruit quality

We report here the identification and characterization of VIGG, a novel virus-induced grapevine protein. Analysis of VIGG expression in grapevine demonstrated that VIGG was constitutively expressed in leaves and stems in virus-infected grapevine, and that VIGG expression was induced by grapevine virus A (GVA) infection, but not by infection with other viruses. The virus-induced expression profile of VIGG was supported by the finding that virus-free meristem cultures prepared from virus-infected grapevines did not express VIGG. An experiment using GFP–VIGG fusion protein demonstrated that VIGG might be localized in or around the endoplasmic reticulum (ER). Treatment of grapevine cells with ER stress inducers resulted in the induction of VIGG expression. Berries from VIGG-expressing grapevines had higher organic acid and phenolic contents than those from control grapevines that did not express VIGG. Interestingly, fruit composition of a grapevine that was simultaneously infected by GVA and grapevine virus B (GVB), which did not express VIGG, was significantly different from that of GVA-infected grapevines expressing VIGG, suggesting that the effector of fruit composition alteration might be VIGG expression, but not GVA infection. Taken together, VIGG expression might suppress the decrease in organic acid content and increase phenol content in berries. Further investigation of the biological function of VIGG is expected to provide new information on the fruit quality of grapevines.     

Linkage isomerism of pentaammine(dimethylsulfoxide)ruthenium(II/III) complexes: A theoretical study

Density functional theory (DFT) calculations have been performed for understanding the linkage isomerism of [Ru^II/III(NH₃)₅(dmso)]^2+/3+ (dmso = dimethylsulfoxide) from a theoretical point of view. In particular, we focus on the interchange between O-bonded and S-bonded structures of the dmso ligand by oxidation/reduction. We have examined five different exchange-correlation functionals (SVWN, BP86, mPWPW91, B3PW91, and B3LYP) in our DFT calculations and found that the relative stabilities of the O-bonded and S-bonded structures are largely dependent on the functional employed. From detailed analyses of atomic charge distributions, it has been found that the calculated atomic charges on the central metal ions are strongly correlated with the relative energies. We also studied the effect of solvation on the linkage isomerism using continuum solvation models.     

TAK1 is critical for IkappaB kinase-mediated activation of the NF-kappaB pathway

Cytokine treatment stimulates the IkappaB kinases, IKKalpha and IKKbeta, which phosphorylate the IkappaB proteins, leading to their degradation and activation of NF-kappaB regulated genes. A clear definition of the specific roles of IKKalpha and IKKbeta in activating the NF-kappaB pathway and the upstream kinases that regulate IKK activity remain to be elucidated. Here, we utilized small interfering RNAs (siRNAs) directed against IKKalpha, IKKbeta and the upstream regulatory kinase TAK1 in order to better define their roles in cytokine-induced activation of the NF-kappaB pathway. In contrast to previous results with mouse embryo fibroblasts lacking either IKKalpha or IKKbeta, which indicated that only IKKbeta is involved in cytokine-induced NF-kappaB activation, we found that both IKKalpha and IKKbeta were important in activating the NF-kappaB pathway. Furthermore, we found that the MAP3K TAK1, which has been implicated in IL-1-induced activation of the NF-kappaB pathway, was also critical for TNFalpha-induced activation of the NF-kappaB pathway. TNFalpha activation of the NF-kappaB pathway is associated with the inducible binding of TAK1 to TRAF2 and both IKKalpha and IKKbeta. This analysis further defines the distinct in vivo roles of IKKalpha, IKKbeta and TAK1 in cytokine-induced activation of the NF-kappaB pathway.