Two novel types of plant hexokinases in the moss Physcomitrella patens
(English)Manuscript (preprint) (Other academic)
Hexokinase catalyzes the phosphorylation of glucose and fructose, but it is also involved in sugar sensing in both fungi and plants. We have previously described two types of hexokinases in the moss Physcomitrella (Olsson et al., 2003, J. Biol. Chem. 278, 44439-44447). Type A, exemplified by the major Physcomitrella hexokinase PpHxk1, is a soluble protein that localizes to the chloroplast stroma. Type B, exemplified by PpHxk2, has an N-terminal membrane anchor. Both types are conserved also in seed plants, and localize to the chloroplast stroma and mitochondrial membranes, respectively. We have now characterized all eleven hexokinases encoded by the Physcomitrella genome. Based on their N-terminal sequences and intracellular localizations, three are type A hexokinases and four type B hexokinases. However, we also found two new types of hexokinases. Type C, encoded by a single gene, has neither transit peptide nor membrane anchor, and is found in the cytosol. Type D hexokinases, encoded by three genes, have membrane anchors and localize to mitochondrial membranes, but their sequences differ significantly from the type B hexokinases. Interestingly, all moss hexokinases are more similar to each other than to hexokinases from other plants. This suggests that the moss genes have undergone concerted evolution.
Hexokinase: Physcomitrella patens: subcellular localization
IdentifiersURN: urn:nbn:se:uu:diva-109192OAI: oai:DiVA.org:uu-109192DiVA: diva2:272024