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91.
Identification of 40k γ-secalin genes 总被引:1,自引:0,他引:1
92.
T. H. Teeri A. Saura J. Lokki 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,69(5-6):567-570
Summary The chloroplast DNA of higher plants is suitable for restriction endonuclease analysis due to its size and homogeneity. We have analysed 48 different cultivars of pea (Pisum sativum) with EcoRI and HindIII. Of these, only 24 show the standard genotype, the remaining 24 comprise four different classes of short insertions, three of which are found at the same site. Even though this kind of insertion polymorphism has not been detected elsewhere in the plant kingdom, it is consistent with the discovery that the chloroplast DNA of pea is destabilised through the loss of an inverted repeat. 相似文献
93.
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96.
Baumann MJ Eklöf JM Michel G Kallas AM Teeri TT Czjzek M Brumer H 《The Plant cell》2007,19(6):1947-1963
High-resolution, three-dimensional structures of the archetypal glycoside hydrolase family 16 (GH16) endo-xyloglucanases Tm-NXG1 and Tm-NXG2 from nasturtium (Tropaeolum majus) have been solved by x-ray crystallography. Key structural features that modulate the relative rates of substrate hydrolysis to transglycosylation in the GH16 xyloglucan-active enzymes were identified by structure-function studies of the recombinantly expressed enzymes in comparison with data for the strict xyloglucan endo-transglycosylase Ptt-XET16-34 from hybrid aspen (Populus tremula x Populus tremuloides). Production of the loop deletion variant Tm-NXG1-DeltaYNIIG yielded an enzyme that was structurally similar to Ptt-XET16-34 and had a greatly increased transglycosylation:hydrolysis ratio. Comprehensive bioinformatic analyses of XTH gene products, together with detailed kinetic data, strongly suggest that xyloglucanase activity has evolved as a gain of function in an ancestral GH16 XET to meet specific biological requirements during seed germination, fruit ripening, and rapid wall expansion. 相似文献
97.
98.
Laitinen RA Ainasoja M Broholm SK Teeri TH Elomaa P 《Journal of experimental botany》2008,59(13):3691-3703
Genetic modification of the flavonoid pathway has been used to produce novel colours and colour patterns in ornamental plants as well as to modify the nutritional and pharmaceutical properties of food crops. It has been suggested that co-ordinate control of multiple steps of the pathway with the help of regulatory genes would lead to a more predictable control of metabolic flux. Regulation of anthocyanin biosynthesis has been studied in a common ornamental plant, Gerbera hybrida (Asteraceae). An R2R3-type MYB factor, GMYB10, shares high sequence similarity and is phylogenetically grouped together with previously characterized regulators of anthocyanin pigmentation. Ectopic expression of GMYB10 leads to strongly enhanced accumulation of anthocyanin pigments as well as to an altered pigmentation pattern in transgenic gerbera plants. Anthocyanin analysis indicates that GMYB10 specifically induces cyanidin biosynthesis in undifferentiated callus and in vegetative tissues. Furthermore, in floral tissues enhanced pelargonidin production is detected. Microarray analysis using the gerbera 9K cDNA array revealed a highly predicted set of putative target genes for GMYB10 including new gene family members of both early and late biosynthetic genes of the flavonoid pathway. However, completely new candidate targets, such as a serine carboxypeptidase-like gene as well, as two new MYB domain factors, GMYB11 and GMYB12, whose exact function in phenylpropanoid biosynthesis is not clear yet, were also identified. 相似文献
99.
Saura-Valls M Fauré R Brumer H Teeri TT Cottaz S Driguez H Planas A 《The Journal of biological chemistry》2008,283(32):21853-21863
Restructuring the network of xyloglucan (XG) and cellulose during plant cell wall morphogenesis involves the action of xyloglucan endo-transglycosylases (XETs). They cleave the XG chains and transfer the enzyme-bound XG fragment to another XG molecule, thus allowing transient loosening of the cell wall and also incorporation of nascent XG during expansion. The substrate specificity of a XET from Populus (PttXET16-34) has been analyzed by mapping the enzyme binding site with a library of xylogluco-oligosaccharides as donor substrates using a labeled heptasaccharide as acceptor. The extended binding cleft of the enzyme is composed of four negative and three positive subsites (with the catalytic residues between subsites -1 and +1). Donor binding is dominated by the higher affinity of the XXXG moiety (G=Glcbeta(1-->4) and X=Xylalpha(1-->6)Glcbeta(1-->4)) of the substrate for positive subsites, whereas negative subsites have a more relaxed specificity, able to bind (and transfer to the acceptor) a cello-oligosaccharyl moiety of hybrid substrates such as GGGGXXXG. Subsite mapping with k(cat)/K(m) values for the donor substrates showed that a GG-unit on negative and -XXG on positive subsites are the minimal requirements for activity. Subsites -2 and -3 (for backbone Glc residues) and +2' (for Xyl substitution at Glc in subsite +2) have the largest contribution to transition state stabilization. GalGXXXGXXXG (Gal=Galbeta(1-->4)) is the best donor substrate with a "blocked" nonreducing end that prevents polymerization reactions and yields a single transglycosylation product. Its kinetics have unambiguously established that the enzyme operates by a ping-pong mechanism with competitive inhibition by the acceptor. 相似文献
100.
Ohlsson AB Djerbi S Winzell A Bessueille L Ståldal V Li X Blomqvist K Bulone V Teeri TT Berglund T 《Protoplasma》2006,228(4):221-229
Summary. Compared to wood, cell suspension cultures provide convenient model systems to study many different cellular processes in
plants. Here we have established cell suspension cultures of Populus tremula L. × P. tremuloides Michx. and characterized them by determining the enzymatic activities and/or mRNA expression levels of selected cell wall-specific
proteins at the different stages of growth. While enzymes and proteins typically associated with primary cell wall synthesis
and expansion were detected in the exponential growth phase of the cultures, the late stationary phase showed high expression
of the secondary-cell-wall-associated cellulose synthase genes. Interestingly, detergent extracts of membranes from aging
cell suspension cultures exhibited high levels of in vitro cellulose synthesis. The estimated ratio of cellulose to callose
was as high as 50 : 50, as opposed to the ratio of 30 : 70 so far achieved with membrane preparations extracted from other
systems. The increased cellulose synthase activity was also evidenced by higher levels of Calcofluor white binding in the
cell material from the stationary-phase cultures. The ease of handling cell suspension cultures and the improved capacity
for in vitro cellulose synthesis suggest that these cultures offer a new basis for studying the mechanism of cellulose biosynthesis.
Correspondence and reprints: School of Biotechnology, Royal Institute of Technology, AlbaNova University Centre, 106 91 Stockholm,
Sweden.
Present address: Department of Biotechnology, Beijing Forestry University, Beijing, People’s Republic of China 相似文献