title: Surface study of apoB1694-1880, a sequence that can anchor apoB to lipoproteins and make it nonexchangeable.
abstract: Apolipoprotein B (apoB) is a nonexchangeable apolipoprotein. During lipoprotein assembly, it recruits phospholipids and triacylglycerols (TAG) into TAG-rich lipoprotein particles. It remains bound to secreted lipoproteins during lipid metabolism in plasma. The beta1 region (residues 827-1880) of apoB has a high amphipathic beta strand (AbetaS) content and is proposed to be one region anchoring apoB to lipoproteins. The AbetaS-rich region between apoB37 and apoB41 (residues 1694-1880) was cloned, expressed, and purified. The interfacial properties were studied at the triolein/water (TO/W) and air/water (A/W) interfaces. ApoB[37-41] is surface-active and adsorbs to the TO/W interface. After adsorption the unbound apoB[37-41] was removed from the aqueous phase. Adsorbed apoB[37-41] did not desorb and could not be forced off by increasing the surface pressure up to 23 mN/m. ApoB[37-41] adsorbed on the TO/W interface was completely elastic when compressed and expanded by +/-13% of its area. On an A/W interface, the apoB[37-41] monolayer became solid when compressed to 4 mN/m pressure indicating extended beta-sheet formation. It could be reversibly compressed and expanded between low pressure and its collapse pressure (35 mN/m). Our studies confirm that the AbetaS structure of apoB[37-41] is a lipid-binding motif that can irreversibly anchor apoB to lipoproteins.
authors.affiliation: Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118-2526, USA.
authors.forename: Libo
authors.initials: L
authors.lastname: Wang
authors.forename: Dale D O
authors.initials: DD
authors.lastname: Martin
authors.forename: Erin
authors.initials: E
authors.lastname: Genter
authors.forename: Jianjun
authors.initials: J
authors.lastname: Wang
authors.forename: Roger S
authors.initials: RS
authors.lastname: McLeod
authors.forename: Donald M
authors.initials: DM
authors.lastname: Small
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D001055:Apolipoproteins B / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004548:Elasticity; D008055:Lipids / Q000737:chemistry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013499:Surface Properties; D014280:Triglycerides / Q000378:metabolism; D014304:Triolein / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D001055:Apolipoproteins B; D008055:Lipids; D010446:Peptide Fragments; D014280:Triglycerides; D014867:Water; D014304:Triolein