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Difference between revisions of "Glycosyltransferase Family 42"
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|'''Active site residues''' | |'''Active site residues''' | ||
| − | |known | + | |His188 is the catalytic base in the Campylobacter jejuni GT-42 known as Cst-II |
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|{{Hl2}} colspan="2" align="center" |'''CAZy DB link''' | |{{Hl2}} colspan="2" align="center" |'''CAZy DB link''' | ||
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== Substrate specificities == | == Substrate specificities == | ||
| − | + | Normal 0 false false false MicrosoftInternetExplorer4 The enzymes in GT-42 were originally examined from isolates of C. jejuni that express a number of ganglioside mimics, some of which have an a-2,8-a-2,3 linked di-sialic acid moiety (Gilbert 2008). The CjGT-42 known as Cst-II was found as part of the LOS biosynthesis operon (Gilbert et al. 2000), which facilitated the correlation of gene content to LOS structure. Based on the LOS structures which contained both a-2,3 and a-2,8 linked sialic acid it was predicted that there should be two sialyltransferases, but the surprising finding was that a single CjGT-42 enzyme, Cst-II, was making both linkages (Gilbert et al. 2002). This bi-functional enzyme has been shown to be a determinant in the development of post-infectious neuropathies (Guillain-Barré syndrome), due to an anti-ganglioside antibody response in some patients who were infected with C. jejuni (Koga et al. 2005) (van Belkum et al. 2001). Some species of Campylobacter express a second GT-42 enzyme known as Cst-I, which was in fact cloned first, but it has been shown not to be involved in LOS biosynthesis on the basis of gene knockouts in strains with both cst genes (Michel Gilbert, personal communication). Cst-I contains an extended C-terminal domain of unknown function, and the target acceptor of this second CjGT-42 is not known at present. The GT-42 family also contains members from H. influenzae and P. multocida, in which the GT-42 enzymes are one of two or three resident sialyltransferases. In H. influenzae the first GT-42 enzyme to be described was the a-2,3-sialyltransferase Lic3A (Hood et al. 2001), followed by a second a-2,3/2,8-bi-functional version known as Lic3B (Fox et al. 2006). In H. influenzae the in vivo acceptor for Lic3A/B is the simple disaccharide lactose in contrast to the more complex ganglioside mimics seen in C. jejuni (Schweda et al. 2007). | |
This is an example of how to make references to a journal article <cite>Comfort2007</cite>. (See the References section below). Multiple references can go in the same place like this <cite>Comfort2007 He1999</cite>. You can even cite books using just the ISBN <cite>3</cite>. References that are not in PubMed can be typed in by hand <cite>MikesClassic</cite>. | This is an example of how to make references to a journal article <cite>Comfort2007</cite>. (See the References section below). Multiple references can go in the same place like this <cite>Comfort2007 He1999</cite>. You can even cite books using just the ISBN <cite>3</cite>. References that are not in PubMed can be typed in by hand <cite>MikesClassic</cite>. | ||
Revision as of 06:24, 15 April 2010
This page is currently under construction. This means that the Responsible Curator has deemed that the page's content is not quite up to CAZypedia's standards for full public consumption. All information should be considered to be under revision and may be subject to major changes.
- Author: ^^^Warren Wakarchuk^^^
- Responsible Curator: ^^^Warren Wakarchuk^^^
| Glycosyltransferase Family GT42 | |
| Clan | GT-x |
| Mechanism | retaining/inverting |
| Active site residues | His188 is the catalytic base in the Campylobacter jejuni GT-42 known as Cst-II |
| CAZy DB link | |
| http://www.cazy.org/fam/GT42.html | |
Substrate specificities
Normal 0 false false false MicrosoftInternetExplorer4 The enzymes in GT-42 were originally examined from isolates of C. jejuni that express a number of ganglioside mimics, some of which have an a-2,8-a-2,3 linked di-sialic acid moiety (Gilbert 2008). The CjGT-42 known as Cst-II was found as part of the LOS biosynthesis operon (Gilbert et al. 2000), which facilitated the correlation of gene content to LOS structure. Based on the LOS structures which contained both a-2,3 and a-2,8 linked sialic acid it was predicted that there should be two sialyltransferases, but the surprising finding was that a single CjGT-42 enzyme, Cst-II, was making both linkages (Gilbert et al. 2002). This bi-functional enzyme has been shown to be a determinant in the development of post-infectious neuropathies (Guillain-Barré syndrome), due to an anti-ganglioside antibody response in some patients who were infected with C. jejuni (Koga et al. 2005) (van Belkum et al. 2001). Some species of Campylobacter express a second GT-42 enzyme known as Cst-I, which was in fact cloned first, but it has been shown not to be involved in LOS biosynthesis on the basis of gene knockouts in strains with both cst genes (Michel Gilbert, personal communication). Cst-I contains an extended C-terminal domain of unknown function, and the target acceptor of this second CjGT-42 is not known at present. The GT-42 family also contains members from H. influenzae and P. multocida, in which the GT-42 enzymes are one of two or three resident sialyltransferases. In H. influenzae the first GT-42 enzyme to be described was the a-2,3-sialyltransferase Lic3A (Hood et al. 2001), followed by a second a-2,3/2,8-bi-functional version known as Lic3B (Fox et al. 2006). In H. influenzae the in vivo acceptor for Lic3A/B is the simple disaccharide lactose in contrast to the more complex ganglioside mimics seen in C. jejuni (Schweda et al. 2007).
This is an example of how to make references to a journal article [1]. (See the References section below). Multiple references can go in the same place like this [1, 2]. You can even cite books using just the ISBN [3]. References that are not in PubMed can be typed in by hand [4].
Kinetics and Mechanism
Content is to be added here.
Catalytic Residues
Content is to be added here.
Three-dimensional structures
Content is to be added here.
Family Firsts
- First stereochemistry determination
- Cite some reference here, with a short (1-2 sentence) explanation [1].
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation [4].
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation [2].
- First 3-D structure
- Cite some reference here, with a short (1-2 sentence) explanation [3].
References
- Comfort DA, Bobrov KS, Ivanen DR, Shabalin KA, Harris JM, Kulminskaya AA, Brumer H, and Kelly RM. (2007). Biochemical analysis of Thermotoga maritima GH36 alpha-galactosidase (TmGalA) confirms the mechanistic commonality of clan GH-D glycoside hydrolases. Biochemistry. 2007;46(11):3319-30. DOI:10.1021/bi061521n |
- He S and Withers SG. (1997). Assignment of sweet almond beta-glucosidase as a family 1 glycosidase and identification of its active site nucleophile. J Biol Chem. 1997;272(40):24864-7. DOI:10.1074/jbc.272.40.24864 |
- Robert V. Stick and Spencer J. Williams. (2009) Carbohydrates. Elsevier Science.
-
Sinnott, M.L. (1990) Catalytic mechanisms of enzymic glycosyl transfer. Chem. Rev. 90, 1171-1202. DOI: 10.1021/cr00105a006