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Mapping the active site of CD59.

Yu J, Abagyan R, Dong S, Gilbert A, Nussenzweig V, Tomlinson S - J. Exp. Med. (1997)

Bottom Line: CD59 is a widely distributed membrane-bound inhibitor of the cytolytic membrane attack complex (MAC) of complement.We present data obtained from a combination of molecular modeling and mutagenesis techniques, which together indicate that the active site of CD59 is located in the vicinity of a hydrophobic groove on the face of the molecule opposite to a "hydrophobic strip" suggested earlier.In addition, removal of the single N-linked glycosylation site at Asn18 of CD59 resulted in an enhancement of complement inhibitory activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, New York University Medical Center, New York 10016, USA.

ABSTRACT
CD59 is a widely distributed membrane-bound inhibitor of the cytolytic membrane attack complex (MAC) of complement. This small (77 amino acid) glycoprotein is a member of the Ly6 superfamily of proteins and is important in protecting host cells from the lytic and proinflammatory activity of the MAC. CD59 functions by binding to C8 and/or C9 in the nascent MAC and interfering with C9 membrane insertion and polymerization. We present data obtained from a combination of molecular modeling and mutagenesis techniques, which together indicate that the active site of CD59 is located in the vicinity of a hydrophobic groove on the face of the molecule opposite to a "hydrophobic strip" suggested earlier. In addition, removal of the single N-linked glycosylation site at Asn18 of CD59 resulted in an enhancement of complement inhibitory activity.

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Related in: MedlinePlus

Amino acid sequence alignment of CD59 and CD59 homologues from different species. The conserved residues located in the  groove that are shown in green in Fig. 7 b are in bold, and conserved residue classes shown in blue in Fig. 7 b are underlined. Residues 16-57 are  shown in plain text. Note that not all of the conserved residues indicated  above occur on the shown surface of the molecule displayed in Fig. 7 b.  The sequences that can be replaced by Ly6E, and which are therefore not  required for function are in italics. Sequences shown are human CD59  (39) and homologues from Baboon (40), Marmoset (41) (GenBank acc.  no. L22860). African green monkey (40), Owl monkey (41) (GenBank  accession no. L22861), Rat (42), and Herpes Saimiri virus (43).
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Figure 6: Amino acid sequence alignment of CD59 and CD59 homologues from different species. The conserved residues located in the groove that are shown in green in Fig. 7 b are in bold, and conserved residue classes shown in blue in Fig. 7 b are underlined. Residues 16-57 are shown in plain text. Note that not all of the conserved residues indicated above occur on the shown surface of the molecule displayed in Fig. 7 b. The sequences that can be replaced by Ly6E, and which are therefore not required for function are in italics. Sequences shown are human CD59 (39) and homologues from Baboon (40), Marmoset (41) (GenBank acc. no. L22860). African green monkey (40), Owl monkey (41) (GenBank accession no. L22861), Rat (42), and Herpes Saimiri virus (43).

Mentions: To reveal the hypothetical location and extent of the functional site, we built a model of the molecular surface of CD59 and analyzed: (a) the three-dimensional location of the fragments that can be replaced by the Ly6E fragments, (b) the distribution of surface patches that are conserved between CD59 of seven different species that are either closely related to human, or that have been shown to inhibit human complement (Fig. 6), and finally, (c) the surface shape. A very clear picture emerged from this analysis. Fig. 7 a displays the molecule in an orientation that shows that the regions of CD59 that can be replaced by Ly6E without loss of function (1-16 and 57-77) are located at the backside of the molecule (in yellow, Fig. 7 a). From the position of residue 77, to which the GPI membrane anchor is attached, it can be predicted that the active site is located on the exposed face of the molecule.


Mapping the active site of CD59.

Yu J, Abagyan R, Dong S, Gilbert A, Nussenzweig V, Tomlinson S - J. Exp. Med. (1997)

Amino acid sequence alignment of CD59 and CD59 homologues from different species. The conserved residues located in the  groove that are shown in green in Fig. 7 b are in bold, and conserved residue classes shown in blue in Fig. 7 b are underlined. Residues 16-57 are  shown in plain text. Note that not all of the conserved residues indicated  above occur on the shown surface of the molecule displayed in Fig. 7 b.  The sequences that can be replaced by Ly6E, and which are therefore not  required for function are in italics. Sequences shown are human CD59  (39) and homologues from Baboon (40), Marmoset (41) (GenBank acc.  no. L22860). African green monkey (40), Owl monkey (41) (GenBank  accession no. L22861), Rat (42), and Herpes Saimiri virus (43).
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Related In: Results  -  Collection

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Figure 6: Amino acid sequence alignment of CD59 and CD59 homologues from different species. The conserved residues located in the groove that are shown in green in Fig. 7 b are in bold, and conserved residue classes shown in blue in Fig. 7 b are underlined. Residues 16-57 are shown in plain text. Note that not all of the conserved residues indicated above occur on the shown surface of the molecule displayed in Fig. 7 b. The sequences that can be replaced by Ly6E, and which are therefore not required for function are in italics. Sequences shown are human CD59 (39) and homologues from Baboon (40), Marmoset (41) (GenBank acc. no. L22860). African green monkey (40), Owl monkey (41) (GenBank accession no. L22861), Rat (42), and Herpes Saimiri virus (43).
Mentions: To reveal the hypothetical location and extent of the functional site, we built a model of the molecular surface of CD59 and analyzed: (a) the three-dimensional location of the fragments that can be replaced by the Ly6E fragments, (b) the distribution of surface patches that are conserved between CD59 of seven different species that are either closely related to human, or that have been shown to inhibit human complement (Fig. 6), and finally, (c) the surface shape. A very clear picture emerged from this analysis. Fig. 7 a displays the molecule in an orientation that shows that the regions of CD59 that can be replaced by Ly6E without loss of function (1-16 and 57-77) are located at the backside of the molecule (in yellow, Fig. 7 a). From the position of residue 77, to which the GPI membrane anchor is attached, it can be predicted that the active site is located on the exposed face of the molecule.

Bottom Line: CD59 is a widely distributed membrane-bound inhibitor of the cytolytic membrane attack complex (MAC) of complement.We present data obtained from a combination of molecular modeling and mutagenesis techniques, which together indicate that the active site of CD59 is located in the vicinity of a hydrophobic groove on the face of the molecule opposite to a "hydrophobic strip" suggested earlier.In addition, removal of the single N-linked glycosylation site at Asn18 of CD59 resulted in an enhancement of complement inhibitory activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, New York University Medical Center, New York 10016, USA.

ABSTRACT
CD59 is a widely distributed membrane-bound inhibitor of the cytolytic membrane attack complex (MAC) of complement. This small (77 amino acid) glycoprotein is a member of the Ly6 superfamily of proteins and is important in protecting host cells from the lytic and proinflammatory activity of the MAC. CD59 functions by binding to C8 and/or C9 in the nascent MAC and interfering with C9 membrane insertion and polymerization. We present data obtained from a combination of molecular modeling and mutagenesis techniques, which together indicate that the active site of CD59 is located in the vicinity of a hydrophobic groove on the face of the molecule opposite to a "hydrophobic strip" suggested earlier. In addition, removal of the single N-linked glycosylation site at Asn18 of CD59 resulted in an enhancement of complement inhibitory activity.

Show MeSH
Related in: MedlinePlus