Stereoselective Interactions of a Specialized Antibody with Cholesterol and Epicholesterol Monolayers

Izhaky, David; Addadi, Lia

doi:10.1002/(sici)1521-3765(20000303)6:5<869::aid-chem869>3.0.co;2-l

Cited by 31 publications

(27 citation statements)

References 11 publications

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“…In contrast, the CDC Thr-Leu pair must recognize specific features of cholesterol at or near the membrane surface to initiate the cholesterol-dependent interaction of the CDC with the cell. Previous studies have demonstrated that the 3-hydroxy headgroup of cholesterol in the 3-β stereoisomer configuration is required for recognition by the CDCs as well as a structurally intact A ring and iso-octyl hydrocarbon chain at C17 (30)(31)(32)(33). Cholesterol is a planar molecule that packs parallel to the phospholipid acyl chains and adopts a nearly perpendicular orientation to the cell surface (34), with the 3-β-hydroxy group at the surface and the iso-octyl chain near the bilayer core.…”

Section: Discussionmentioning

confidence: 99%

Only two amino acids are essential for cytolytic toxin recognition of cholesterol at the membrane surface

Farrand

LaChapelle

Hotze

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

195

279

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The recognition and binding of cholesterol is an important feature of many eukaryotic, viral, and prokaryotic proteins, but the molecular details of such interactions are understood only for a few proteins. The pore-forming cholesterol-dependent cytolysins (CDCs) contribute to the pathogenic mechanisms of a large number of Grampositive bacteria. Cholesterol dependence of the CDC mechanism is a hallmark of these toxins, yet the identity of the CDC cholesterol recognition motif has remained elusive. A detailed analysis of membrane interactive structures at the tip of perfringolysin O (PFO) domain 4 reveals that a threonine-leucine pair mediates CDC recognition of and binding to membrane cholesterol. This motif is conserved in all known CDCs and conservative changes in its sequence or order are not well tolerated. Thus, the Thr-Leu pair constitutes a common structural basis for mediating CDC-cholesterol recognition and binding, and defines a unique paradigm for membrane cholesterol recognition by surface-binding proteins.M embrane cholesterol is important to a variety of pathogenic processes that include virus fusion and budding (1) and the mechanisms of eukaryotic (2, 3) and prokaryotic toxins (4-7). Whether cholesterol is bound directly by these proteins as a receptor or it indirectly influences the binding or activity of the protein at the membrane surface remains unknown. The cholesterol-dependent cytolysins (CDCs) use cholesterol as their receptor at the membrane surface (7) and contribute to the pathogenesis of a large number of Gram-positive bacterial pathogens (8). The CDC-sterol interaction initiates a cascade of secondary and tertiary structural changes that lead to the formation of a large oligomeric complex, and ultimately a pore in the membrane of eukaryotic cells (9-13). Although significant progress has been made in understanding the assembly of the CDC pore complex, the structural basis for recognition and binding to cholesterol-rich membranes remains elusive.Early studies with the Clostridium perfringens perfringolysin O (PFO) suggested that the highly conserved tryptophan-rich undecapeptide sequence at the base of domain 4 (14, 15) (Fig. S1) mediated the PFO-cholesterol interaction. However, recent studies by Soltani et al. (16) uncoupled cholesterol binding from the undecapeptide and showed that the membrane insertion of loops L1-L3 at the base of domain 4 was cholesterol dependent (Fig. S1). These observations are also consistent with a lack of conservation of the 3D structures of the undecapeptide in the closely related CDCs PFO (17) and Bacillus anthracis anthrolysin O (ALO) (18) (Fig. S1). These studies suggest the residues that comprise the cholesterol recognition motif are located within L1-L3 because these loops and the undecapeptide are the only structures at the tip of domain 4 exposed to the nonpolar bilayer core; the rest of the domain 4 surface is surrounded by water (19).Cholesterol was thought to function as the sole CDC receptor until the discovery of intermedilysin (ILY), a CDC fr...

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Section: Discussionmentioning

confidence: 99%

Only two amino acids are essential for cytolytic toxin recognition of cholesterol at the membrane surface

Farrand

LaChapelle

Hotze

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

195

279

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“…[203±205] On the other hand, some mechanisms have been identified that enhance crystallization. [141] Currently discussed, especially for the case of atherosclerosis, are: * the heterogeneous nucleation of calcium phosphates on the membranes of dead cells that contain phospholipids (phosphate groups act as nucleators), [192,195] * nucleation by antibodies that are specific for cholesterol, [205,206] and * cellular action of osteoblast-like cells (so-called pericytes) within arteries that form bonelike tissue. [207] For the case of atherosclerosis, obviously a number of effects are responsible for the pathological calcification; these range from purely physicochemical effects (supersaturation) [141] over biologically induced nucleation to the biologically controlled deposition of calcium phosphates by specialized cells.…”

Section: Reviewsmentioning

confidence: 99%

Biological and Medical Significance of Calcium Phosphates

Dorozhkin¹,

Epple²

2002

Angew. Chem. Int. Ed.

1,836

1,252

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The inorganic part of hard tissues (bones and teeth) of mammals consists of calcium phosphate, mainly of apatitic structure. Similarly, most undesired calcifications (i.e. those appearing as a result of various diseases) of mammals also contain calcium phosphate. For example, atherosclerosis results in blood-vessel blockage caused by a solid composite of cholesterol with calcium phosphate. Dental caries result in a replacement of less soluble and hard apatite by more soluble and softer calcium hydrogenphosphates. Osteoporosis is a demineralization of bone. Therefore, from a chemical point of view, processes of normal (bone and teeth formation and growth) and pathological (atherosclerosis and dental calculus) calcifications are just an in vivo crystallization of calcium phosphate. Similarly, dental caries and osteoporosis can be considered to be in vivo dissolution of calcium phosphates. On the other hand, because of the chemical similarity with biological calcified tissues, all calcium phosphates are remarkably biocompatible. This property is widely used in medicine for biomaterials that are either entirely made of or coated with calcium phosphate. For example, self-setting bone cements made of calcium phosphates are helpful in bone repair and titanium substitutes covered with a surface layer of calcium phosphates are used for hip-joint endoprostheses and tooth substitutes, to facilitate the growth of bone and thereby raise the mechanical stability. Calcium phosphates have a great biological and medical significance and in this review we give an overview of the current knowledge in this subject.

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“…The antibody that recognizes the face of cholesterol monohydrate crystals also recognizes cholesterol molecules in a monolayer at the air-water interface, while antibodies that are not specific to cholesterol crystals do not. Moreover, the same antibody does not interact with monolayers of epicholesterol, showing fine stereochemical/structural discrimination between arrays of isomeric steroids (34). The antibody affinity to the cholesterol monolayers is so high that labeling by the antibody is observed in equilibrium with a residual concentration in solution as low as 10 -11 M (35).…”

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confidence: 99%