title: Cytoplasmic domain of zebrafish myelin protein zero: adhesive role depends on beta-conformation.
abstract: Solution spectroscopy studies on the cytoplasmic domain of human myelin protein zero (P0) (hP0-cyt) suggest that H-bonding between beta-strands from apposed molecules is likely responsible for the tight cytoplasmic apposition in compact myelin. As a follow-up to these findings, in the current study we used circular dichroism and x-ray diffraction to analyze the same type of model membranes previously used for hP0-cyt to investigate the molecular mechanism underlying the zebrafish cytoplasmic apposition. This space is significantly narrower in teleosts compared with that in higher vertebrates, and can be accounted for in part by the much shorter cytoplasmic domain in the zebrafish protein (zP0-cyt). Circular dichroism measurements on zP0-cyt showed similar structural characteristics to those of hP0-cyt, i.e., the protein underwent a beta-->alpha structural transition at lipid/protein (L/P) molar ratios >50, and adopted a beta-conformation at lower L/P molar ratios. X-ray diffraction was carried out on lipid vesicle solutions with zP0-cyt before and after dehydration to study the effect of protein on membrane lipid packing. Solution diffraction revealed the electron-density profile of a single membrane bilayer. Diffraction patterns of dried samples suggested a multilamellar structure with the beta-folded P0-cyt located at the intermembrane space. Our findings support the idea that the adhesive role of P0 at the cytoplasmic apposition in compact myelin depends on the cytoplasmic domain of P0 being in the beta-conformation.
authors: Department of Biology, Boston College, Chestnut Hill, Massachusetts, USA.
authors: XiaoYang
authors: X
authors: Luo
authors: Hideyo
authors: H
authors: Inouye
authors: Abby A R
authors: AA
authors: Gross
authors: Marla M
authors: MM
authors: Hidalgo
authors: Deepak
authors: D
authors: Sharma
authors: Daniel
authors: D
authors: Lee
authors: Robin L
authors: RL
authors: Avila
authors: Mario
authors: M
authors: Salmona
authors: Daniel A
authors: DA
authors: Kirschner
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D015233:Models, Statistical; D008969:Molecular Sequence Data; D018993:Myelin P0 Protein / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014961:X-Ray Diffraction; D015027:Zebrafish
chemical_list: D008051:Lipid Bilayers; D008055:Lipids; D018993:Myelin P0 Protein; D010455:Peptides
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