Reovirus hemagglutinin (sigma 1) - Revision history

Carole Weaver: /* Glycan profiling */

2011-09-15T17:21:32Z

Glycan profiling

Kurt Drickamer: /* Biosynthesis of ligands */

2011-04-11T08:45:55Z

Biosynthesis of ligands

Carole Weaver: /* Glycogene microarray */

2011-03-30T23:24:06Z

Glycogene microarray

Carole Weaver: /* Glycogene microarray */

2011-03-28T19:12:19Z

Glycogene microarray

Carole Weaver: /* Knockout mouse lines */

2011-03-21T19:56:39Z

Knockout mouse lines

Carole Weaver: /* Related GBPs */

2011-03-21T19:55:15Z

Related GBPs

Anna Crie at 17:01, 2 July 2010

2010-07-02T17:01:17Z

Show changes

Carole Weaver at 22:57, 21 June 2010

2010-06-21T22:57:08Z

Show changes

Anna Crie at 04:20, 15 June 2010

2010-06-15T04:20:20Z

Anna Crie at 03:59, 15 June 2010

2010-06-15T03:59:59Z

Show changes

@@ Line 37: / Line 37: @@
 === Glycan profiling ===
-Not performed.
+Not applicable.
 === Glycogene microarray ===

@@ Line 20: / Line 20: @@
 Reovirus employs a multi-step mechanism of viral attachment in which a low-affinity interaction with sialic acid serves to tether the virion to target cells and precedes a high-affinity interaction with JAM-A<ref name="Barton2001a">.</ref>, an immunoglobulin superfamily protein engaged by reovirus<ref name="Barton2001b">Barton, E.S., Forrest, J.C., Connolly, J.L., Chappell, J.D., Liu, Y., Schnell, F., Nusrat, A., Parkos, C.A., and Dermody, T.S. Junction adhesion molecule is a receptor for reovirus. Cell 104:441-451, 2001.</ref><ref>Prota, A.E., Campbell, J.A., Schelling, P., Forrest, J.C., Peters, T.R., Watson, M.J., Aurrand-Lions, M., Imhof, B., Dermody, T.S., and Stehle, T. Crystal structure of human junctional adhesion molecule 1: implications for reovirus binding. Proc. Natl. Acad. Sci. U. S. A. 100:5366-5371, 2003.</ref><ref>Campbell, J.A., Shelling, P., Wetzel, J.D., Johnson, E.M., Wilson, G.A.R., Forrest, J.C., Aurrand-Lions, M., Imhof, B., Stehle, T., and Dermody, T.S. Junctional adhesion molecule-A serves as a receptor for prototype and field-isolate strains of mammalian reovirus. J. Virol. 79:7967-7978, 2005.</ref>. By virtue of its rapid association rate, virus binding to sialic acid adheres the virion to the cell surface, thereby enabling it to diffuse laterally until it encounters JAM-A. Such lateral diffusion has been reported for influenza virus<ref>Sagik, B., Puck, T., and Levine, S. Quantitative aspects of the spontaneous elution of influenza virus from red cells. J. Exp. Med. 99:251-260, 1954.</ref> and phage T4<ref>Wilson, J.H., Luftig, R.B., and Wood, W.B. Interaction of bacteriophage T4 tail fiber components with a lipopolysaccharide fraction from Escherichia coli. J. Mol. Biol. 51:423-434, 1970.</ref>. After attachment, reovirus is internalized by receptor-mediated endocytosis<ref>Borsa, J., Morash, B.D., Sargent, M.D., Copps, T.P., Lievaart, P.A., and Szekely, J.G. Two modes of entry of reovirus particles into L cells. J. Gen. Virol. 45:161-170, 1979.</ref><ref>Borsa, J., Sargent, M.D., Lievaart, P.A., and Copps, T.P. Reovirus: evidence for a second step in the intracellular uncoating and transcriptase activation process. Virology 111:191-200, 1981.</ref><ref>Ehrlich, M., Boll, W., Van Oijen, A., Hariharan, R., Chandran, K., Nibert, M.L., and Kirchhausen, T. Endocytosis by random initiation and stabilization of clathrin-coated pits. Cell 118:591-605, 2004.</ref><ref name="Maginnis2006">Maginnis, M.S., Forrest, J.C., Kopecky-Bromberg, S.A., Dickeson, S.K., Santoro, S.A., Zutter, M.M., Nemerow, G.R., Bergelson, J.M., and Dermody, T.S. b1 integrin mediates internalization of mammalian reovirus. J. Virol. 80:2760-2770, 2006.</ref><ref>Sturzenbecker, L.J., Nibert, M.L., Furlong, D.B., and Fields, B.N. Intracellular digestion of reovirus particles requires a low pH and is an essential step in the viral infectious cycle. J. Virol. 61:2351-2361, 1987.</ref><ref name="Maginnis2008">Maginnis, M.S., Mainou, B.A., Derdowski, A.M., Johnson, E.M., Zent, R., and Dermody, T.S. NPXY motifs in the b1 integrin cytoplasmic tail are required for functional reovirus entry. J. Virol. 82:3181-3191, 2008.</ref> using a mechanism dependent on beta 1 integrin<ref name="Maginnis2006">.</ref><ref name="Maginnis2008">.</ref>.
 === Biosynthesis of ligands ===
 <br>
 === Structure ===
 Structural analysis of the C-terminal half of reovirus attachment protein sigma 1 from strain T3D (residues 246-455) reveals a trimeric structure, in which each monomer is composed of a slender tail and a compact head<ref name="Chappell2002">.</ref>. The C-terminal residues that form the head domain (310-455) consist of two Greek-key motifs that fold into a beta-barrel. The sigma 1 head domain binds to JAM-A<ref name="Barton2001b">.</ref><ref>Kirchner, E., Guglielmi, K.M., Strauss, H.M., Dermody, T.S., and Stehle, T. Structure of reovirus s1 in complex with its receptor junctional adhesion molecule-A. PLoS Path. 4:e1000235, 2008.</ref>. N-terminal residues in the crystallized fragment form a portion of the tail, residues 246-309, which consists of three beta-spiral repeats. Each repeat is composed of two short beta-strands connected by a four-residue beta-turn that has either a proline or a glycine residue at its third position<ref name="Chappell2002">.</ref>. A surface-exposed, variable loop links successive repeats, and trimerization generates an unusual triple beta-spiral motif that also is observed in the adenovirus fiber<ref>van Raaij, M.J., Mitraki, A., Lavigne, G., and Cusack, S. A triple b-spiral in the adenovirus fibre shaft reveals a new structural motif for a fibrous protein. Nature 401:935-938, 1999.</ref>, bacteriophage PRD1 P5 protein<ref>Merckel, M.C., Huiskonen, J.T., Bamford, D.H., Goldman, A., and Tuma, R. The structure of the bacteriophage PRD1 spike sheds light on the evolution of viral capsid architecture. Mol. Cell 18:161-170, 2005.</ref>, and avian reovirus attachment protein sigma C<ref>Guardado, C.P., Fox, G.C., Hermo Parrado, X.L., Llamas-Saiz, A.L., Costas, C., Martinez-Costas, J., Benavente, J., and van Raaij, M.J. Structure of the carboxy-terminal receptor-binding domain of avian reovirus fibre sigmaC. J. Mol. Biol. 354:137-149, 2005.</ref>.

@@ Line 38: / Line 38: @@
 === Glycogene microarray ===
-Not applicable, as the CFG microarrays only contain probes for mouse and human glycogenes.
+Sigma 1 is not represented on the CFG microarrays, which only contain probes for mouse and human glycogenes.
 === Knockout mouse lines ===

@@ Line 38: / Line 38: @@
 === Glycogene microarray ===
-Not performed.
+Not applicable, as the CFG microarrays only contain probes for mouse and human glycogenes.
 === Knockout mouse lines ===

@@ Line 41: / Line 41: @@
 === Knockout mouse lines ===
-Not tested.
+Not applicable.
 === Glycan array ===

@@ Line 47: / Line 47: @@
 == Related GBPs ==
-The attachment protein of adenovirus, fiber, is a structural homolog of sigma 1. At least one adenovirus serotype (Ad37) is known to bind glycan receptors via residues in the fiber protein<ref>Burmeister WP, Guilligay D, Cusack S, Wadell G, Arnberg N: Crystal structure of species D adenovirus fiber knobs and their sialic acid binding sites. Journal of Virology 78:7727-7736, 2004.</ref>. The actual binding site is not homologous. However, information about reovirus glycan binding could also be used to engineer adenovirus fiber proteins (or other trimeric fiber-like proteins) that possess novel glycan-binding properties.
+The attachment protein of adenovirus, fiber, is a structural homolog of sigma 1. At least one adenovirus serotype (Ad37; [http://www.functionalglycomics.org/glycomics/search/jsp/landing.jsp?query=ad37&maxresults=20 CFG data]) is known to bind glycan receptors via residues in the fiber protein<ref>Burmeister WP, Guilligay D, Cusack S, Wadell G, Arnberg N: Crystal structure of species D adenovirus fiber knobs and their sialic acid binding sites. Journal of Virology 78:7727-7736, 2004.</ref>. The actual binding site is not homologous. However, information about reovirus glycan binding could also be used to engineer adenovirus fiber proteins (or other trimeric fiber-like proteins) that possess novel glycan-binding properties.
 == References ==

@@ Line 18: / Line 18: @@
 Serotype 1 reoviruses are incapable of infecting MEL cells, which support infection only by sialic-acid-binding strains<ref name="name1">.</ref>. Serotype 1 reoviruses also are insensitive to the growth-inhibitory effects of neuraminidase treatment of L929 cells<ref name="name5">.</ref>. However, binding of serotype 1 reoviruses to intestinal M cells is diminished by neuraminidase treatment<ref name="name10">.</ref>. The explanation for this discrepancy is not known.
-Reovirus employs a multi-step mechanism of viral attachment in which a low-affinity interaction with sialic acid serves to tether the virion to target cells and precedes a high-affinity interaction with JAM-A<ref name="name9">.</ref>, an immunoglobulin superfamily protein engaged by reovirus<ref>Barton, E.S., Forrest, J.C., Connolly, J.L., Chappell, J.D., Liu, Y., Schnell, F., Nusrat, A., Parkos, C.A., and Dermody, T.S. Junction adhesion molecule is a receptor for reovirus. Cell 104:441-451, 2001.</ref><ref>Prota, A.E., Campbell, J.A., Schelling, P., Forrest, J.C., Peters, T.R., Watson, M.J., Aurrand-Lions, M., Imhof, B., Dermody, T.S., and Stehle, T. Crystal structure of human junctional adhesion molecule 1: implications for reovirus binding. Proc. Natl. Acad. Sci. U. S. A. 100:5366-5371, 2003.</ref><ref>Campbell, J.A., Shelling, P., Wetzel, J.D., Johnson, E.M., Wilson, G.A.R., Forrest, J.C., Aurrand-Lions, M., Imhof, B., Stehle, T., and Dermody, T.S. Junctional adhesion molecule-A serves as a receptor for prototype and field-isolate strains of mammalian reovirus. J. Virol. 79:7967-7978, 2005.</ref>. By virtue of its rapid association rate, virus binding to sialic acid adheres the virion to the cell surface, thereby enabling it to diffuse laterally until it encounters JAM-A. Such lateral diffusion has been reported for influenza virus<ref>Sagik, B., Puck, T., and Levine, S. Quantitative aspects of the spontaneous elution of influenza virus from red cells. J. Exp. Med. 99:251-260, 1954.</ref> and phage T4<ref>Wilson, J.H., Luftig, R.B., and Wood, W.B. Interaction of bacteriophage T4 tail fiber components with a lipopolysaccharide fraction from Escherichia coli. J. Mol. Biol. 51:423-434, 1970.</ref>. After attachment, reovirus is internalized by receptor-mediated endocytosis<ref>Borsa, J., Morash, B.D., Sargent, M.D., Copps, T.P., Lievaart, P.A., and Szekely, J.G. Two modes of entry of reovirus particles into L cells. J. Gen. Virol. 45:161-170, 1979.</ref><ref>Borsa, J., Sargent, M.D., Lievaart, P.A., and Copps, T.P. Reovirus: evidence for a second step in the intracellular uncoating and transcriptase activation process. Virology 111:191-200, 1981.</ref><ref>Ehrlich, M., Boll, W., Van Oijen, A., Hariharan, R., Chandran, K., Nibert, M.L., and Kirchhausen, T. Endocytosis by random initiation and stabilization of clathrin-coated pits. Cell 118:591-605, 2004.</ref><ref>Maginnis, M.S., Forrest, J.C., Kopecky-Bromberg, S.A., Dickeson, S.K., Santoro, S.A., Zutter, M.M., Nemerow, G.R., Bergelson, J.M., and Dermody, T.S. b1 integrin mediates internalization of mammalian reovirus. J. Virol. 80:2760-2770, 2006.</ref><ref>Sturzenbecker, L.J., Nibert, M.L., Furlong, D.B., and Fields, B.N. Intracellular digestion of reovirus particles requires a low pH and is an essential step in the viral infectious cycle. J. Virol. 61:2351-2361, 1987.</ref><ref>Maginnis, M.S., Mainou, B.A., Derdowski, A.M., Johnson, E.M., Zent, R., and Dermody, T.S. NPXY motifs in the b1 integrin cytoplasmic tail are required for functional reovirus entry. J. Virol. 82:3181-3191, 2008.</ref> using a mechanism dependent on beta 1 integrin<ref>Maginnis, M.S., Forrest, J.C., Kopecky-Bromberg, S.A., Dickeson, S.K., Santoro, S.A., Zutter, M.M., Nemerow, G.R., Bergelson, J.M., and Dermody, T.S. b1 integrin mediates internalization of mammalian reovirus. J. Virol. 80:2760-2770, 2006.</ref><ref>Maginnis, M.S., Mainou, B.A., Derdowski, A.M., Johnson, E.M., Zent, R., and Dermody, T.S. NPXY motifs in the b1 integrin cytoplasmic tail are required for functional reovirus entry. J. Virol. 82:3181-3191, 2008.</ref>.
+Reovirus employs a multi-step mechanism of viral attachment in which a low-affinity interaction with sialic acid serves to tether the virion to target cells and precedes a high-affinity interaction with JAM-A<ref name="name9">.</ref>, an immunoglobulin superfamily protein engaged by reovirus<ref name="name11">Barton, E.S., Forrest, J.C., Connolly, J.L., Chappell, J.D., Liu, Y., Schnell, F., Nusrat, A., Parkos, C.A., and Dermody, T.S. Junction adhesion molecule is a receptor for reovirus. Cell 104:441-451, 2001.</ref><ref>Prota, A.E., Campbell, J.A., Schelling, P., Forrest, J.C., Peters, T.R., Watson, M.J., Aurrand-Lions, M., Imhof, B., Dermody, T.S., and Stehle, T. Crystal structure of human junctional adhesion molecule 1: implications for reovirus binding. Proc. Natl. Acad. Sci. U. S. A. 100:5366-5371, 2003.</ref><ref>Campbell, J.A., Shelling, P., Wetzel, J.D., Johnson, E.M., Wilson, G.A.R., Forrest, J.C., Aurrand-Lions, M., Imhof, B., Stehle, T., and Dermody, T.S. Junctional adhesion molecule-A serves as a receptor for prototype and field-isolate strains of mammalian reovirus. J. Virol. 79:7967-7978, 2005.</ref>. By virtue of its rapid association rate, virus binding to sialic acid adheres the virion to the cell surface, thereby enabling it to diffuse laterally until it encounters JAM-A. Such lateral diffusion has been reported for influenza virus<ref>Sagik, B., Puck, T., and Levine, S. Quantitative aspects of the spontaneous elution of influenza virus from red cells. J. Exp. Med. 99:251-260, 1954.</ref> and phage T4<ref>Wilson, J.H., Luftig, R.B., and Wood, W.B. Interaction of bacteriophage T4 tail fiber components with a lipopolysaccharide fraction from Escherichia coli. J. Mol. Biol. 51:423-434, 1970.</ref>. After attachment, reovirus is internalized by receptor-mediated endocytosis<ref>Borsa, J., Morash, B.D., Sargent, M.D., Copps, T.P., Lievaart, P.A., and Szekely, J.G. Two modes of entry of reovirus particles into L cells. J. Gen. Virol. 45:161-170, 1979.</ref><ref>Borsa, J., Sargent, M.D., Lievaart, P.A., and Copps, T.P. Reovirus: evidence for a second step in the intracellular uncoating and transcriptase activation process. Virology 111:191-200, 1981.</ref><ref>Ehrlich, M., Boll, W., Van Oijen, A., Hariharan, R., Chandran, K., Nibert, M.L., and Kirchhausen, T. Endocytosis by random initiation and stabilization of clathrin-coated pits. Cell 118:591-605, 2004.</ref><ref name="name12">Maginnis, M.S., Forrest, J.C., Kopecky-Bromberg, S.A., Dickeson, S.K., Santoro, S.A., Zutter, M.M., Nemerow, G.R., Bergelson, J.M., and Dermody, T.S. b1 integrin mediates internalization of mammalian reovirus. J. Virol. 80:2760-2770, 2006.</ref><ref>Sturzenbecker, L.J., Nibert, M.L., Furlong, D.B., and Fields, B.N. Intracellular digestion of reovirus particles requires a low pH and is an essential step in the viral infectious cycle. J. Virol. 61:2351-2361, 1987.</ref><ref name="name13">Maginnis, M.S., Mainou, B.A., Derdowski, A.M., Johnson, E.M., Zent, R., and Dermody, T.S. NPXY motifs in the b1 integrin cytoplasmic tail are required for functional reovirus entry. J. Virol. 82:3181-3191, 2008.</ref> using a mechanism dependent on beta 1 integrin<ref name="name12">.</ref><ref name="name13">.</ref>.
 === Structure ===
-<br>Structural analysis of the C-terminal half of reovirus attachment protein sigma 1 from strain T3D (residues 246-455) reveals a trimeric structure, in which each monomer is composed of a slender tail and a compact head<ref name="name6">.</ref>. The C-terminal residues that form the head domain (310-455) consist of two Greek-key motifs that fold into a beta-barrel. The sigma 1 head domain binds to JAM-A<ref>Barton, E.S., Forrest, J.C., Connolly, J.L., Chappell, J.D., Liu, Y., Schnell, F., Nusrat, A., Parkos, C.A., and Dermody, T.S. Junction adhesion molecule is a receptor for reovirus. Cell 104:441-451, 2001.</ref><ref>Kirchner, E., Guglielmi, K.M., Strauss, H.M., Dermody, T.S., and Stehle, T. Structure of reovirus s1 in complex with its receptor junctional adhesion molecule-A. PLoS Path. 4:e1000235, 2008.</ref>. N-terminal residues in the crystallized fragment form a portion of the tail, residues 246-309, which consists of three beta-spiral repeats. Each repeat is composed of two short beta-strands connected by a four-residue beta-turn that has either a proline or a glycine residue at its third position<ref name="name6">.</ref>. A surface-exposed, variable loop links successive repeats, and trimerization generates an unusual triple beta-spiral motif that also is observed in the adenovirus fiber<ref>van Raaij, M.J., Mitraki, A., Lavigne, G., and Cusack, S. A triple b-spiral in the adenovirus fibre shaft reveals a new structural motif for a fibrous protein. Nature 401:935-938, 1999.</ref>, bacteriophage PRD1 P5 protein<ref>Merckel, M.C., Huiskonen, J.T., Bamford, D.H., Goldman, A., and Tuma, R. The structure of the bacteriophage PRD1 spike sheds light on the evolution of viral capsid architecture. Mol. Cell 18:161-170, 2005.</ref>, and avian reovirus attachment protein sigma C<ref>Guardado, C.P., Fox, G.C., Hermo Parrado, X.L., Llamas-Saiz, A.L., Costas, C., Martinez-Costas, J., Benavente, J., and van Raaij, M.J. Structure of the carboxy-terminal receptor-binding domain of avian reovirus fibre sigmaC. J. Mol. Biol. 354:137-149, 2005.</ref>.
+<br>Structural analysis of the C-terminal half of reovirus attachment protein sigma 1 from strain T3D (residues 246-455) reveals a trimeric structure, in which each monomer is composed of a slender tail and a compact head<ref name="name6">.</ref>. The C-terminal residues that form the head domain (310-455) consist of two Greek-key motifs that fold into a beta-barrel. The sigma 1 head domain binds to JAM-A<ref name="name11">.</ref><ref>Kirchner, E., Guglielmi, K.M., Strauss, H.M., Dermody, T.S., and Stehle, T. Structure of reovirus s1 in complex with its receptor junctional adhesion molecule-A. PLoS Path. 4:e1000235, 2008.</ref>. N-terminal residues in the crystallized fragment form a portion of the tail, residues 246-309, which consists of three beta-spiral repeats. Each repeat is composed of two short beta-strands connected by a four-residue beta-turn that has either a proline or a glycine residue at its third position<ref name="name6">.</ref>. A surface-exposed, variable loop links successive repeats, and trimerization generates an unusual triple beta-spiral motif that also is observed in the adenovirus fiber<ref>van Raaij, M.J., Mitraki, A., Lavigne, G., and Cusack, S. A triple b-spiral in the adenovirus fibre shaft reveals a new structural motif for a fibrous protein. Nature 401:935-938, 1999.</ref>, bacteriophage PRD1 P5 protein<ref>Merckel, M.C., Huiskonen, J.T., Bamford, D.H., Goldman, A., and Tuma, R. The structure of the bacteriophage PRD1 spike sheds light on the evolution of viral capsid architecture. Mol. Cell 18:161-170, 2005.</ref>, and avian reovirus attachment protein sigma C<ref>Guardado, C.P., Fox, G.C., Hermo Parrado, X.L., Llamas-Saiz, A.L., Costas, C., Martinez-Costas, J., Benavente, J., and van Raaij, M.J. Structure of the carboxy-terminal receptor-binding domain of avian reovirus fibre sigmaC. J. Mol. Biol. 354:137-149, 2005.</ref>.
-In addition to the three beta-spiral repeats observed in the crystallized sigma 1 fragment, sequence analysis suggests that residues 167-249 in the T3D sigma 1 tail form an additional five N-terminal beta-spiral repeats<ref name="name6">.</ref><ref>Guglielmi, K.M., Johnson, E.M., Stehle, T., and Dermody, T.S. Attachment and cell entry of mammalian orthoreovirus. Curr. Top. Microbiol. Immunol. 309:1-38, 2006.</ref>. Alternatively, these residues may form a combination of beta-spiral repeats and alpha-helical coiled-coil, as suggested by sequence analysis<ref name="name6">.</ref><ref>Guglielmi, K.M., Johnson, E.M., Stehle, T., and Dermody, T.S. Attachment and cell entry of mammalian orthoreovirus. Curr. Top. Microbiol. Immunol. 309:1-38, 2006.</ref><ref>Nibert, M.L., Dermody, T.S., and Fields, B.N. Structure of the reovirus cell-attachment protein: a model for the domain organization of s1. J. Virol. 64:2976-2989, 1990.</ref> and an observed narrowing in this region in a composite negative-stain electron micrograph<ref>Fraser, R.D.B., Furlong, D.B., Trus, B.L., Nibert, M.L., Fields, B.N., and Steven, A.C. Molecular structure of the cell-attachment protein of reovirus: correlation of computer-processed electron micrographs with sequence-based predictions. J. Virol. 64:2990-3000, 1990.</ref>. The structure of N-terminal residues 1-160 of sigma 1 is unknown. However, a repeating heptad sequence motif is predictive of an amphipathic alpha-helix, which likely assembles into an alpha-helical coiled-coil in the trimer<ref name="name6">.</ref><ref>Guglielmi, K.M., Johnson, E.M., Stehle, T., and Dermody, T.S. Attachment and cell entry of mammalian orthoreovirus. Curr. Top. Microbiol. Immunol. 309:1-38, 2006.</ref><ref>Nibert, M.L., Dermody, T.S., and Fields, B.N. Structure of the reovirus cell-attachment protein: a model for the domain organization of s1. J. Virol. 64:2976-2989, 1990.</ref>.
+In addition to the three beta-spiral repeats observed in the crystallized sigma 1 fragment, sequence analysis suggests that residues 167-249 in the T3D sigma 1 tail form an additional five N-terminal beta-spiral repeats<ref name="name6">.</ref><ref name="name14">Guglielmi, K.M., Johnson, E.M., Stehle, T., and Dermody, T.S. Attachment and cell entry of mammalian orthoreovirus. Curr. Top. Microbiol. Immunol. 309:1-38, 2006.</ref>. Alternatively, these residues may form a combination of beta-spiral repeats and alpha-helical coiled-coil, as suggested by sequence analysis<ref name="name6">.</ref><ref name="name14">.</ref><ref name="name15">Nibert, M.L., Dermody, T.S., and Fields, B.N. Structure of the reovirus cell-attachment protein: a model for the domain organization of s1. J. Virol. 64:2976-2989, 1990.</ref> and an observed narrowing in this region in a composite negative-stain electron micrograph<ref>Fraser, R.D.B., Furlong, D.B., Trus, B.L., Nibert, M.L., Fields, B.N., and Steven, A.C. Molecular structure of the cell-attachment protein of reovirus: correlation of computer-processed electron micrographs with sequence-based predictions. J. Virol. 64:2990-3000, 1990.</ref>. The structure of N-terminal residues 1-160 of sigma 1 is unknown. However, a repeating heptad sequence motif is predictive of an amphipathic alpha-helix, which likely assembles into an alpha-helical coiled-coil in the trimer<ref name="name6">.</ref><ref name="name14">.</ref><ref name="name15">.</ref>.
 Although the structure of sigma 1 in complex with sialic acid is not yet available, studies using expressed proteins indicate that the region of T3D sigma 1 required for sialic binding resides near the midpoint of the tail, whereas a region just N-terminal to the head domain of T1L sigma 1 binds to carbohydrate<ref name="name7">.</ref>. In both T1L and T3D sigma 1, interactions with carbohydrate are mediated by a region of predicted beta-spiral<ref name="name6">.</ref>. Adaptation of non-sialic-acid-binding reoviruses to growth in MEL cells results in amino acid substitutions at residues 198, 202, and 204 of sigma 1 that confer sialic-acid-binding capacity on the resultant viruses<ref name="name8">.</ref>. Molecular modeling of the sigma 1 tail, based on available structure and sequence data, suggests that these residues are surface-exposed and proximal to one another in the predicted beta-spiral region<ref name="name6">.</ref>. Thus, residues 198, 202, and 204 are likely to contribute to a sialic-acid-binding site in T3D sigma 1.
@@ Line 46: / Line 46: @@
 == Related GBPs ==
-The attachment protein of adenovirus, fiber, is a structural homolog of sigma 1. At least one adenovirus serotype (Ad37) is known to bind glycan receptors via residues in the fiber protein<ref>Burmeister WP, Guilligay D, Cusack S, Wadell G, Arnberg N: Crystal structure of species D adenovirus fiber knobs and their sialic acid binding sites. Journal of Virology 2004, 78:7727-7736.</ref>. The actual binding site is not homologous. However, information about reovirus glycan binding could also be used to engineer adenovirus fiber proteins (or other trimeric fiber-like proteins) that possess novel glycan-binding properties.
+The attachment protein of adenovirus, fiber, is a structural homolog of sigma 1. At least one adenovirus serotype (Ad37) is known to bind glycan receptors via residues in the fiber protein<ref>Burmeister WP, Guilligay D, Cusack S, Wadell G, Arnberg N: Crystal structure of species D adenovirus fiber knobs and their sialic acid binding sites. Journal of Virology 78:7727-7736, 2004.</ref>. The actual binding site is not homologous. However, information about reovirus glycan binding could also be used to engineer adenovirus fiber proteins (or other trimeric fiber-like proteins) that possess novel glycan-binding properties.
 == References ==