TY  - GEN
TI  - Biochemical Characterization of the Sec14-PH Module from the Neurofibromatosis Type I Protein
KW  - Neurofibromin 
KW  -  Sec14 
KW  -  pleckstrin homology 
KW  -  phosphatidylethanolamin 
KW  -  lipids
Y1  - 2008///
ID  - heidok8902
N2  - Neurofibromatosis type I (NF1) is an inherited neurocutaneous disorder with a high incidence of 1 in 3500 newborns. Clinical manifestations include pigment anomalies, Lisch nodules and the formation of different tumors like neurofibroma. NF1 is caused by alterations of the NF1 gene, encoding the Ras specific GTPase activating protein Neurofibromin, which participates in several major signaling pathways. A structural proteomics approach recently led to the discovery of an unpredicted pleckstrin homology (PH)- and a Sec14-like domain. In this thesis I have investigated the biochemical properties of the NF1-SecPH module. NF1-SecPH can bind glycerophospholipids with a preference for phosphatidylethanolamine and -glycerol (PtdEtn, -Gro), of which PtdEtn is abundant in Neurofibromin containing cells and thus a likely physiological ligand. It was furthermore possible to crystallize NF1-SecPH in complex with glycerophospholipids which is the first structure of a CRAL Trio domain bound to such ligands and shows that PtdEtn binds to the interior of the Nf1-Sec portion. Lipid exchange experiments revealed that PtdEtn and PtdGro are readily exchanged, but phosphatidylcholine, -serine and -inositol (PtdCho, -Ser, -Ins) are only incorporated to a minor degree. The lipid exchange activity can be modulated by soluble headgroups of phosphorylated PtdIns derivatives (PIPs), which is consistent with a regulatory interaction between Nf1-Sec and NF1-PH. While some patient derived mutants show significant structural alterations compared to the cellular NF1-SecPH module, their properties with respect to lipid content and PIP binding are only affected slightly. Localization studies in the presence and absence of stimuli did not reveal a specific compartment association compared to other PH domain containing proteins. Taken together, PtdEtn is probably a physiological ligand of NF1- SecPH, which seems able to incorporate membrane derived lipids in a regulated fashion.
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/8902/
AV  - public
A1  - Welti, Stefan
ER  -