Elucidation of structural and antigenic properties of pneumococcal serotype 11A, 11B, 11C, and 11F polysaccharide capsules

Despite the emerging impact of serogroup 11 serotypes in Streptococcus pneumoniae epidemiology, the structures of serogroup 11 capsule types have not been fully elucidated, particularly the locations of O-acetyl substitutions. Here, we report the complete structures of the serotype 11B, 11C, and 11F polysaccharides and a revision to the serotype 11A capsular polysaccharide using nuclear magnetic resonance (NMR). All structures shared a linear, tetrasaccharide backbone with a pendant phosphopolyalcohol. Three of four saccharides are conserved in all serotypes. The individual serotype capsules differed in the identity of one saccharide, the pendant phosphopolyalcohol, and the O-acetylation pattern. Though the assigned locations of O-acetate substitutions in this study differed from those of previous reports, our findings were corroborated with strong correlations to serology and genetics. We examined the binding of serotyping sera to serogroup 11 polysaccharides by using flow cytometry and an inhibition-type enzyme-linked immunosorbent assay (ELISA) and found that de-O-acetylation of capsular polysaccharides by mild hydrolysis decreases its immunoreactivity, supporting the crucial role of O-acetylation in the antigenicity of these polysaccharides. Due to strong correlations between polysaccharide structures and capsule biosynthesis genes, we were able to assign target substrates for the O-acetyltransferases encoded by wcwC, wcwR, wcwT, and wcjE. We identified antigenic determinants for serogroup 11 serotyping sera and highlight the idea that conventional serotyping methods are not capable of recognizing all putative variants of S. pneumoniae serogroup 11.     

Design, synthesis, and biological evaluation of cytotoxic 11-aminoalkenylindenoisoquinoline and 11-diaminoalkenylindenoisoquinoline topoisomerase I inhibitors

The cytotoxic indenoisoquinolines are a novel class of noncamptothecin topoisomerase I inhibitors having certain features that compare favorably with the camptothecins. A new strategy was adopted to attach aminoalkenyl substituents at C-11 of the indenoisoquinoline ring system, which, according to molecular modeling, would orient the side chains toward the DNA minor groove. All of the newly synthesized compounds were more cytotoxic than the parent indenoisoquinoline NSC 314622. Despite an imperfect correlation between cytotoxicities and topoisomerase I inhibition results, the hypothetical structural model of the cleavage complex presented here provides a conceptual framework to explain the structure-activity relationships.     

Characterization of a Rab11 homologue, EoRab11a, in Euplotes octocarinatus

Rab GTPases are crucial in the regulation of intracellular vesicular trafficking. A novel Rab GTPase gene, EoRab11a (GenBank accession no. EF061065 ), was isolated and identified from Euplotes octocarinatus cells in this study. It contains an ORF of 696-bp nucleotides, encoding 231 amino acids with a calculated molecular weight of 26.8 kDa. Alignment of EoRab11a with other Rab11 proteins from other eukaryotes demonstrated that these proteins shared 53–61% identity at the amino acid level. The recombinant EoRab11a was expressed in Escherichia coli and purified by immobilized metal chelate affinity chromatography and iron chromatography. The GTPase activity of EoRab11a was 0.0024 min⁻¹ detected by HPLC at 30 °C. Three mutations were generated at amino acids Ser21 and Gly22 positions in the G1 domain of EoRab11a. All three mutants, S21P, S21G and G22R, increased the GTPase activity in vitro . Immunofluorescence microscopy results indicated that EoRab11a was localized on the phagosomal membrane during phagocytosis of E. octocarinatus . These data show that EoRab11a possesses GTP hydrolysis activity and may participate in vesicle transport events during phagocytosis of E. octocarinatus .     

Dolastatin 11 conformations, analogues and pharmacophore

Twenty analogues of the natural antitumor agent dolastatin 11, including majusculamide C, were synthesized and tested for cytotoxicity against human cancer cells and stimulation of actin polymerization. Only analogues containing the 30-membered ring were active. Molecular modeling and NMR evidence showed the low-energy conformations. The amide bonds are all trans except for the one between the Tyr and Val units, which is cis. Since an analogue restricted to negative 2-3-4-5 angles stimulated actin polymerization but was inactive in cells, the binding conformation (most likely the lowest-energy conformation in water) has a negative 2-3-4-5 angle, whereas a conformation with a positive 2-3-4-5 angle (most likely the lowest energy conformation in chloroform) goes through cell walls. The highly active R alcohol from borohydride reduction of dolastatin 11 is a candidate for conversion to prodrugs.     

Myosin V, Rab11, and dRip11 direct apical secretion and cellular morphogenesis in developing Drosophila photoreceptors

Sensory neuron terminal differentiation tasks apical secretory transport with delivery of abundant biosynthetic traffic to the growing sensory membrane. We recently showed Drosophila Rab11 is essential for rhodopsin transport in developing photoreceptors and asked here if myosin V and the Drosophila Rab11 interacting protein, dRip11, also participate in secretory transport. Reduction of either protein impaired rhodopsin transport, stunting rhabdomere growth and promoting accumulation of cytoplasmic rhodopsin. MyoV-reduced photoreceptors also developed ectopic rhabdomeres inappropriately located in basolateral membrane, indicating a role for MyoV in photoreceptor polarity. Binary yeast two hybrids and in vitro protein-protein interaction predict a ternary complex assembled by independent dRip11 and MyoV binding to Rab11. We propose this complex delivers morphogenic secretory traffic along polarized actin filaments of the subcortical terminal web to the exocytic plasma membrane target, the rhabdomere base. A protein trio conserved across eukaryotes thus mediates normal, in vivo sensory neuron morphogenesis.     

Synthesis of the Pink Bollworm Sex Pheromone, 7-cis, 11-cis-Hexadecadienyl Acetate and Its 11-trans Isomer

Four types of amino acid related compounds were examined on their plant growth-regulating activity. These compounds were N-acylamino acids (N-acyl), N-alkylamino acids (N-alkyl), amino acid higher alkyl esters (ester) and amino acid higher alkyl amides (amide). Every compound, when the number of carbon atoms of the acyl or alkyl radical was 10 to 12, was most effective in inhibiting the root and shoot elongation of rice plant (Oryza sativa L.) in Petri dish. Ester and amide were much more effective than N-acyl and N-alkyl. Ester and amide also showed herbicidal activity against barnyardgrass (Echinochloa crusgalli) grown in pot filled with paddy soil and irrigated, especially, lauryl dl-valinate-HCl being most effective.     

Serum steroid hormones including 11-ketotestosterone, 11-ketoandrostenedione, and dihydroprogesterone in juvenile and adult bonnethead sharks, Sphyrna tiburo.

Previous studies in the placental viviparous bonnethead shark, Sphyrna tiburo, have correlated 17 beta-estradiol, progesterone, testosterone, and dihydrotestosterone with reproductive events in both males and females. However, several key reproductive events, including implantation, maintenance of pregnancy, and parturition, did not correlate with these four steroid hormones. Therefore, the present study investigated three steroid hormones, 11-ketotestosterone, 11-ketoandrostenedione, and dihydroprogesterone, which have demonstrably important roles in the reproductive cycles of teleosts. It was hypothesized that one or more of these three hormones would correlate with specific reproductive events in S. tiburo. Concurrently, developmental (growth and/or maturation) analyses of these three steroids plus 17 beta-estradiol, progesterone, testosterone, and dihydrotestosterone were investigated in juvenile bonnethead sharks. Serum dihydroprogesterone concentrations were highest in mature females and 11-ketotestosterone concentrations were highest in mature males. In mature females, 11-ketoandrostenedione levels were elevated from the time of mating, through six months of sperm storage and another four months of gestation. At parturition concentrations became significantly lower and remained lower until mating occurred again in another two to three months. Serum 11-ketotestosterone concentrations were the highest at implantation though not significant. In mature males, significantly elevated serum levels of dihydroprogesterone occurred in April and May, near the start of annual testicular development. During growth in males, testosterone and dihydrotestosterone increased progressively and in females, testosterone increased progressively. At maturity in males, significant increases occurred in testosterone and 11-ketotestosterone concentrations while, in females, dihydroprogesterone, 11-ketotestosterone, 17 beta-estradiol, progesterone, testosterone, and dihydrotestosterone concentrations increased. This study shows that although testosterone may be the primary androgen in the bonnethead shark, other derived androgens may have important functions in growth, maturation, and reproduction. J. Exp. Zool. 284:595-603, 1999.     

Conservation of XYN11A and XYN11B xylanase genes in Bipolaris sorghicola,Cochliobolus sativus,Cochliobolus heterostrophus,and Cochliobolus spicifer

Two types of xylanase gene, XYN11A (XYL1) and XYN11B (XYL2), were amplified by PCR and partially sequenced in four phytopathogenic species of the ascomycete fungal genus Cochliobolus (anamorph genus Bipolaris). Three of the species, C. heterostrophus (B. maydis), C. sativus (B. sorokiniana), and Bipolaris sorghicola (no teleomorph known), are interrelated; the fourth, C. spicifer (B. spicifera), was found, through analysis of the 5.8S RNA and internal transcribed spacer (ITS) sequences of its ribosomal DNA, to be more distantly related to the other three. Isolates from all four species contain orthologous XYN11A and XYN11B genes, but a set of laboratory strains of C. heterostrophus gave no product corresponding to the XYN11B gene. The patterns of evolution of the two xylanase genes and ribosomal DNA sequences are mutually consistent; the results indicate that the two genes were present in the common ancestor of all Cochliobolus species and are evolving independently of each other. Received: 12 July 2001 / Accepted: 6 March 2002     

Rab11的结构特征、效应因子与功能

Rab11是Rab小分子GTP酶家族的成员.在细胞内膜泡再循环途径中,Rab11作为重要调节因子,介导膜泡从内体向质膜的运输.近年来随着对Rab11研究的深入,人们发现该蛋白质在多种细胞生命活动中发挥着关键作用.现对Rab11的结构、效应蛋白及功能等方面进行了综述.