title: Rigidity of wedge loop in PACSIN 3 protein is a key factor in dictating diameters of tubules.
abstract: BAR (Bin/amphiphysin/Rvs) domain-containing proteins participate in cellular membrane remodeling. The F-BAR proteins normally generate low curvature tubules. However, in the PACSIN subfamily, the F-BAR domain from PACSIN 1 and 2 can induce both high and low curvature tubules. We found that unlike PACSIN 1 and 2, PACSIN 3 could only induce low curvature tubules. To elucidate the key factors that dictate the tubule curvature, crystal structures of all three PACSIN F-BAR domains were determined. A novel type of lateral interaction mediated by a wedge loop is observed between the F-BAR neighboring dimers. Comparisons of the structures of PACSIN 3 with PACSIN 1 and 2 indicate that the wedge loop of PACSIN 3 is more rigid, which influences the lateral interactions between assembled dimers. We further identified the residues that affect the rigidity of the loop by mutagenesis and determined the structures of two PACSIN 3 wedge loop mutants. Our results suggest that the rigidity-mediated conformations of the wedge loop correlate well with the various crystal packing modes and membrane tubulations. Thus, the rigidity of the wedge loop is a key factor in dictating tubule diameters.
authors.affiliation: State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Bai
authors.forename: Geng
authors.initials: G
authors.lastname: Meng
authors.forename: Ming
authors.initials: M
authors.lastname: Luo
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zheng
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D018360:Crystallography, X-Ray / Q000379:methods; D019281:Dimerization; D006046:Gold / Q000737:chemistry; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000502:physiology*; D008081:Liposomes / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D047908:Intracellular Signaling Peptides and Proteins; D008081:Liposomes; C421762:PACSIN3 protein, human; D006046:Gold