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báo cáo khoa học: " Two novel types of hexokinases in the moss Physcomitrella patens"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Two novel types of hexokinases in the moss Physcomitrella patens | Nilsson et al. BMC Plant Biology 2011 11 32 http www.biomedcentral.com 1471-2229 11 32 BMC Plant Biology RESEARCH ARTICLE Open Access Two novel types of hexokinases in the moss Physcomitrella patens 1 - - z-sI 2 1 2 1 Anders Nilsson T Tina Olsson T Mikael Ulfstedt Mattias Thelander Hans Ronne Abstract Background 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. Type A exemplified by PpHxk1 the major hexokinase in Physcomitrella is a soluble protein that localizes to the chloroplast stroma. Type B exemplified by PpHxk2 has an N-terminal membrane anchor. Both types are found also in vascular plants and localize to the chloroplast stroma and mitochondrial membranes respectively. Results We have now characterized all 11 hexokinase encoding genes in Physcomitrella. Based on their N-terminal sequences and intracellular localizations three of the encoded proteins are type A hexokinases and four are type B hexokinases. One of the type B hexokinases has a splice variant without a membrane anchor that localizes to the cytosol and the nucleus. However we also found two new types of hexokinases with no obvious orthologs in vascular plants. Type C encoded by a single gene has neither transit peptide nor membrane anchor and is found in the cytosol and in the nucleus. Type D hexokinases encoded by three genes have membrane anchors and localize to mitochondrial membranes but their sequences differ from those of the type B hexokinases. Interestingly all moss hexokinases are more similar to each other in overall sequence than to hexokinases from other plants even though characteristic sequence motifs such as the membrane anchor of the type B hexokinases are highly conserved between moss and vascular plants indicating a common origin for hexokinases of the same type. Conclusions We conclude that the hexokinase gene family