TY - JOUR
T1 - Crystal and solution structures of fragments of the human leucocyte common antigen-related protein
AU - Vilstrup, Joachim
AU - Simonsen, Amanda
AU - Birkefeldt, Thea
AU - Strandbygård, Dorthe
AU - Lyngsø, Jeppe
AU - Pedersen, Jan Skov
AU - Thirup, Søren
PY - 2020/5
Y1 - 2020/5
N2 - Leucocyte common antigen-related protein (LAR) is a post-synaptic type I transmembrane receptor protein that is important for neuronal functionality and is genetically coupled to neuronal disorders such as attention deficit hyperactivity disorder (ADHD). To understand the molecular function of LAR, structural and biochemical studies of protein fragments derived from the ectodomain of human LAR have been performed. The crystal structure of a fragment encompassing the first four FNIII domains (LARFN1-4) showed a characteristic L shape. SAXS data suggested limited flexibility within LARFN1-4, while rigid-body refinement of the SAXS data using the X-ray-derived atomic model showed a smaller angle between the domains defining the L shape compared with the crystal structure. The capabilities of the individual LAR fragments to interact with heparin was examined using microscale thermophoresis and heparin-affinity chromatography. The results showed that the three N-terminal immunoglobulin domains (LARIg1-3) and the four C-terminal FNIII domains (LARFN5-8) both bound heparin, while LARFN1-4 did not. The low-molecular-weight heparin drug Innohep induced a shift in hydrodynamic volume as assessed by size-exclusion chromatography of LARIg1-3 and LARFN5-8, while the chemically defined pentameric heparin drug Arixtra did not. Together, the presented results suggest the presence of an additional heparin-binding site in human LAR.
AB - Leucocyte common antigen-related protein (LAR) is a post-synaptic type I transmembrane receptor protein that is important for neuronal functionality and is genetically coupled to neuronal disorders such as attention deficit hyperactivity disorder (ADHD). To understand the molecular function of LAR, structural and biochemical studies of protein fragments derived from the ectodomain of human LAR have been performed. The crystal structure of a fragment encompassing the first four FNIII domains (LARFN1-4) showed a characteristic L shape. SAXS data suggested limited flexibility within LARFN1-4, while rigid-body refinement of the SAXS data using the X-ray-derived atomic model showed a smaller angle between the domains defining the L shape compared with the crystal structure. The capabilities of the individual LAR fragments to interact with heparin was examined using microscale thermophoresis and heparin-affinity chromatography. The results showed that the three N-terminal immunoglobulin domains (LARIg1-3) and the four C-terminal FNIII domains (LARFN5-8) both bound heparin, while LARFN1-4 did not. The low-molecular-weight heparin drug Innohep induced a shift in hydrodynamic volume as assessed by size-exclusion chromatography of LARIg1-3 and LARFN5-8, while the chemically defined pentameric heparin drug Arixtra did not. Together, the presented results suggest the presence of an additional heparin-binding site in human LAR.
KW - ectodomain
KW - heparin binding
KW - leucocyte common antigen-related protein
KW - protein tyrosine phosphatase receptor
KW - SAXS
KW - synaptogenesis
KW - X-ray crystallography
UR - http://www.scopus.com/inward/record.url?scp=85084277064&partnerID=8YFLogxK
U2 - 10.1107/S2059798320003885
DO - 10.1107/S2059798320003885
M3 - Journal article
C2 - 32355037
AN - SCOPUS:85084277064
SN - 2059-7983
VL - 76
SP - 406
EP - 417
JO - Acta crystallographica Section D: Structural biology
JF - Acta crystallographica Section D: Structural biology
ER -