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Functional characterization of hexokinases in the moss Physcomitrella patens

Olsson, Tina (2005). Functional characterization of hexokinases in the moss Physcomitrella patens. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2005:78
ISBN 91-576-6977-5
[Doctoral thesis]

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Abstract

Carbohydrates are important nutrients and structural components in all living organisms. In plants they affect the developmental and metabolic processes throughout the plant life cycle. However, the mechanisms by which plants recognise and respond to carbohydrates are mainly unknown. Hexokinase, an enzyme that mediates the first catalytic step in hexose metabolism, has recently been suggested to be involved in sugar sensing and signalling in plants. The moss Physcomitrella patens has recently emerged as a powerful model system in plant functional genomics following the discovery that gene targeting works in it with frequencies comparable to those in yeast. The aim of this thesis was to learn more about the function of plant hexokinases, both as key metabolic enzymes and in their putative role as sensors in sugar signalling, using Physcomitrella patens as a model system. Five hexokinases from Physcomitrella patens were cloned and studied with respect to their subcellular localizations. PpHxk1 and PpHxk5 are located in the stroma of chloroplasts and are dependent on N-terminal transit peptides for correct localization. PpHxk2 and PpHxk3 both contain hydrophobic membrane anchors that localize the proteins to the outer envelope of chloroplasts. PpHxk4 contain neither a transit peptide nor an anchor, and is found in the cytosol. A targeted knockout revealed that PpHxk1 is the major hexokinase in Physcomitrella, accounting for 80% of the glucose phosphorylating activity. Consistent with this, the knockout mutant exhibits an artificial starvation phenotype with altered sensitivities to plant hormones and a disturbed development.

Authors/Creators:Olsson, Tina
Title:Functional characterization of hexokinases in the moss Physcomitrella patens
Year of publishing :September 2005
Volume:2005:78
Number of Pages:36
Papers/manuscripts:
NumberReferences
ALLI. Olsson, T., Thelander, M. & Ronne, H. 2003. A novel type of chloroplast stromal hexokinase is the major glucose phosphorylating enzyme in the moss Physcomitrella patens. Journal of Biological Chemistry 278, 44439-44447. II. Thelander, M., Olsson, T. & Ronne, H. 2005. Effect of the energy supply on filamentous growth and development in Physcomitrella patens. Journal of Experimental Botany 56, 653-662. III. Olsson, T., Nilsson, A., Thelander, M. & Ronne, H. 2005. Structure and localization of hexokinases in the moss Physcomitrella patens. (Manuscript).
Place of Publication:Uppsala
ISBN for printed version:91-576-6977-5
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F60 Plant physiology and biochemistry
Subjects:Not in use, please see Agris categories
Agrovoc terms:hexokinase, bryophyta, monosaccharides, chloroplasts, cloning, energy metabolism
Keywords:Physcomitrella patens, sugar signalling, subcellular localization, chloroplast, carbohydrate
URN:NBN:urn:nbn:se:slu:epsilon-746
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-746
ID Code:936
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Tina Olsson
Deposited On:22 Sep 2005 00:00
Metadata Last Modified:02 Dec 2014 10:08

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