Anders Backlund

Phylogeny of the eudicots : a nearly complete familial analysis based on rbcL gene sequences

A phylogenetic analysis of 589 plastid rbcL gene sequences representing nearly all eudicot families (a total of 308 families; seven photosynthetic and four parasitic families are missing) was performed, and bootstrap re-sampling was used to assess support for clades. Based on these data, the ordinal classification of eudicots is revised following the previous classification of angiosperms by the Angiosperm Phylogeny Group (APG). Putative additional orders are discussed (e.g. Dilleniales, Escalloniales, Vitales), and several additional families are assigned to orders for future updates of the APG classification. The use of rbcL alone in such a large matrix was found to be practical in discovering and providing bootstrap support for most orders. Combination of these data with other matrices for the rest of the angiosperms should provide the framework for a complete phylogeny to be used in macro-evolutionary studies.

Structure and function of Rubisco

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the major enzyme assimilating CO(2) into the biosphere. At the same time Rubisco is an extremely inefficient catalyst and its carboxylase activity is compromised by an opposing oxygenase activity involving atmospheric O(2). The shortcomings of Rubisco have implications for crop yield, nitrogen and water usage, and for the global carbon cycle. Numerous high-resolution crystal structures of different forms of Rubisco are now available, including structures of mutant enzymes. This review uses the information provided in these structures in a structure-based sequence alignment and discusses Rubisco function in the context of structural variations at all levels--amino acid sequence, fold, tertiary and quaternary structure--with an evolutionary perspective and an emphasis on the structural features of the enzyme that may determine its function as a carboxylase.

Novel chemical space exploration via natural products.

Natural products (NPs) are a rich source of novel compound classes and new drugs. In the present study we have used the chemical space navigation tool ChemGPS-NP to evaluate the chemical space occupancy by NPs and bioactive medicinal chemistry compounds from the database WOMBAT. The two sets differ notably in coverage of chemical space, and tangible leadlike NPs were found to cover regions of chemical space that lack representation in WOMBAT. Property based similarity calculations were performed to identify NP neighbors of approved drugs. Several of the NPs revealed by this method were confirmed to exhibit the same activity as their drug neighbors. The identification of leads from a NP starting point may prove a useful strategy for drug discovery in the search for novel leads with unique properties.

Functional Constraints and rbcL Evidence for Land Plant Phylogeny

Although the proportion of «functional» DNA in eukaryotic genomes is both debatable and subject to definition, most sequences gathered for phylogenetic purposes are indisputably functional. For example, patterns of variation are likely to be strongly constrained in ribosomal RNAs because of their structural and catalytic roles in protein translation, and in protein-coding genes, because of protein function itself. Although seemingly obvious, these concerns are usually ignored by workers producing gene trees. We have examined the extent of functional constraints in land-plant rbcL sequences. Not only do rbcL sequences appear to change with essentially clocklike regularity, but nucleotide-based cladograms imply tbat approximately 97.5% of codon changes on internal branches are functionally neutral (i.e., synonymous or functionally labile)

Phylogeny of theAsterales sensu lato based onrbcL sequences with particular reference to theGoodeniaceae

TherbcL gene of 25 taxa was sequenced and analyzed cladistically in order to define more precisely the orderAsterales s.l. and to reconstruct the phylogeny ofGoodeniaceae. The cladistic analyses show that theAsterales comprise the familiesAbrophyllaceae, Alseuosmiaceae, Argophyllaceae, Asteraceae, Calyceraceae, Campanulaceae s.l.,Donatiaceae, Goodeniaceae (includingBrunoniaceae),Menyanthaceae, Pentaphragmataceae, andStylidiaceae. Abrophyllaceae, Alseuosmiaceae, Brunoniaceae, andDonatiaceae have previously not been studied in this respect. Within theGoodeniaceae, four groups supported by therbcL data can be distinguished: the genusLechenaultia, theAnthotium-Dampiera-group, the genusBrunonia, and a group formed by the remaining genera, theScaevola-Goodenia-group.

ChemGPS-NPWeb: chemical space navigation online

Internet has become a central source for information, tools, and services facilitating the work for medicinal chemists and drug discoverers worldwide. In this paper we introduce a web-based public tool, ChemGPS-NPWeb (http://chemgps.bmc.uu.se), for comprehensive chemical space navigation and exploration in terms of global mapping onto a consistent, eight dimensional map over structure derived physico-chemical characteristics. ChemGPS-NPWeb can assist in compound selection and prioritization; property description and interpretation; cluster analysis and neighbourhood mapping; as well as comparison and characterization of large compound datasets. By using ChemGPS-NPWeb, researchers can analyze and compare chemical libraries in a consistent manner. In this study it is demonstrated how ChemGPS-NPWeb can assist in interpreting results from two large datasets tested for activity in biological assays for pyruvate kinase and Bcl-2 family related protein interactions, respectively. Furthermore, a more than 30-year-old suggestion of “chemical similarity” between the natural pigments betalains and muscaflavins is tested.

Phylogeny of the Asteridae s. str. based on rbcL sequences, with particular reference to the Dipsacales

TherbcL gene of 15 taxa was sequenced and analyzed cladistically together with a large sample of genera representing all main clades of the subclassAsteridae in order to determine more precisely the delimitation of the orderDipsacales and to elucidate the phylogeny of the families within the order. The cladistic analyses show that the Dipsacales comprise the familiesCaprifoliaceae, Morinaceae, Dipsacaceae, andValerianaceae includingTriplostegia. The results also provide a basis for the exclusion of a number of taxa previously placed in theDipsacales, such asDesfontainia, Columellia andAdoxaceae s. l. (includingSambucus andViburnum). Ever since the orderDipsacales was first suggested byDumortier (1829) and the similarCaprifoliales byLindley (1833, 1836), there has been confusion concerning the circumscription of the order, the relations between the included families, their circumscriptions, and the position of the order in a larger context.

Primary and 3-D modelled structures of two cyclotides from Viola odorata.

Two polypeptides named vodo M and vodo N, both of 29 amino acids, have been isolated from Viola odorata L. (Violaceae) using ion exchange chromatography and reversed phase HPLC. The sequences were determined by automated Edman degradation, quantitative amino acid analysis, and mass spectrometry (MS). Using MS, it was established that vodo M (cyclo-SWPVCTRNGAPICGESCFTGKCYTVQCSC) and vodo N (cyclo-SWPVCYRNGLPVCGETCTLGKCYTAGCSC) form a head-to-tail cyclic backbone and that six cysteine residues are involved in three disulphide bonds. Their origin, sequences, and cyclic nature suggest that these peptides belong to the family of cyclic plant peptides, called cyclotides. The three-dimensional structures of vodo M and vodo N were modelled by homology, using the experimentally determined structure of the cyclotide kalata B1 as the template. The images of vodo M and vodo N show amphipathic structures with considerable surface hydrophobicity for a protein modelled in a polar environment.

A phylogenetic analysis of 100+ genera and 50+ families of euasterids based on morphological and molecular data with notes on possible higher level morphological synapomorphies

Abstract. A data matrix of 143 morphological and chemical characters for 142 genera of euasterids according to the APG system was compiled and complemented with rbcL and ndhF sequences for most of the genera. The data were subjected to parsimony analysis and support was assessed by bootstrapping. Strict consensus trees from analyses of morphology alone and morphology + rbcL + ndhF are presented. The morphological data recover several groups supported by molecular data but at the level of orders and above relationships are only superficially in agreement with molecular studies. The analyses provide support for monophyly of Gentianales, Aquifoliales, Apiales, Asterales, and Dipsacales. All data indicate that Adoxaceae are closely related to Dipsacales and hence they should be included in that order. The trees were used to assess some possible morphological synapomorphies for euasterids I and II and for the orders of the APG system. Euasterids I are generally characterised by opposite leaves, entire leaf margins, hypogynous flowers, “early sympetaly” with a ring-shaped corolla primordium, fusion of stamen filaments with the corolla tube, and capsular fruits. Euasterids II often have alternate leaves, serrate-dentate leaf margins, epigynous flowers, “late sympetaly” with distinct petal primordia, free stamen filaments, and indehiscent fruits. It is unclear which of these characters represent synapomorphies and symplesiomorphies for the two groups, respectively, and there are numerous expections to be interpreted as reversals and parallelisms.

Novel Trisubstituted Harmine Derivatives with Original in Vitro Anticancer Activity

To overcome the intrinsic resistance of cancer cells to apoptotic stimuli, we designed and synthesized approximately 50 novel β-carbolines structurally related to harmine. Harmine is known for its anticancer properties and is a DYRK1A inhibitor. Of the synthesized compounds, the most active in terms of growth inhibition of five cancer cell lines are cytostatic and approximately 100 times more potent than harmine but demonstrated no DYRK1A inhibitory activity. These novel β-carbolines display similar growth inhibitory activity in cancer cells that are sensitive and resistant to apoptotic stimuli. Using ChemGPS-NP, we found that the more active β-carbolines are all more lipophilic and larger than the less active compounds. Lastly, on the basis of the NCI human tumor cell line anticancer drug screen and the NCI COMPARE algorithm, it appears that some of these compounds, including 5a and 5k, seem to act as protein synthesis inhibitors.