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Difference between revisions of "Glycoside Hydrolase Family 58"
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== Three-dimensional structures == | == Three-dimensional structures == | ||
| − | + | The structure for the K1F tailspike enzyme has been solved by Stummeyeret al. <cite>5<cite/>. The protein structure is similar to other phage tailspike endo-hydrolases in that it is a an extended molecule that is trimeric. | |
| − | |||
== Family Firsts == | == Family Firsts == | ||
Revision as of 07:19, 23 October 2009
The text below is a template to help you create a consistent layout for GH entries. To get an idea of what to put in each field, save this edit and have a look at any of the GH families by following this link: Category:Glycoside Hydrolase Families (TIP: Right click with your mouse and open the link in a new browser window...)
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- Author: ^^^Warren Wakarchuk^^^
- Responsible Curator: ^^^Warren Wakarchuk^^^
| Glycoside Hydrolase Family GH58 | |
| Clan | none |
| Mechanism | inverting |
| Active site residues | known/not known |
| CAZy DB link | |
| http://www.cazy.org/fam/GHnn.html | |
Substrate specificities
endo-N-acetylneuraminidase or endo-sialidase
The capsular coat surrounding E. coli K1, protects the bacterium from degradation by the host immune system, but it also acts as an anchor point for bacteriophage infection. The capsular material for K1 is poly-a-2,8-sialic acid and a range of bacteriophages specific to this E. coli capsule type have been described [1, 2]
This is an example of how to make references to a journal article [3]. (See the References section below). Multiple references can go in the same place like this [3, 4]. You can even cite books using just the ISBN [5]. References that are not in PubMed can be typed in by hand [6].
Kinetics and Mechanism
This enzyme is specific for polysialic acid and is one of a unique family of endo-sialidases, all others previously reported being exo-sialidases. The recently determined structure of an endosialidase derived from bacteriophage K1F (endoNF)[5] revealed the active site to lack a number of the residues that are conserved in other sialidases, implying a new, endosialidase-specific catalytic mechanism. Using synthetic trifluoromethylumbelliferyl oligosialoside substrates kinetic parameters for hydrolysis at a single cleavage site were determined. Measurement of kcat/Km at a series of pH values revealed a dependence on a single protonated group of pKa 5. Direct 1H-NMR analysis of the hydrolysis of trifluoromethylumbelliferyl sialotrioside revealed that endoNF is an inverting sialidase [1].
Catalytic Residues
Content is to be added here.
Three-dimensional structures
The structure for the K1F tailspike enzyme has been solved by Stummeyeret al. [2, 3, 7, 7, 8, 9, 10, 11, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39].
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation [6].
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation [4].
- First 3-D structure
- Cite some reference here, with a short (1-2 sentence) explanation [5].
References
- Hallenbeck PC, Vimr ER, Yu F, Bassler B, and Troy FA. (1987). Purification and properties of a bacteriophage-induced endo-N-acetylneuraminidase specific for poly-alpha-2,8-sialosyl carbohydrate units. J Biol Chem. 1987;262(8):3553-61. | Google Books | Open Library
- Petter JG and Vimr ER. (1993). Complete nucleotide sequence of the bacteriophage K1F tail gene encoding endo-N-acylneuraminidase (endo-N) and comparison to an endo-N homolog in bacteriophage PK1E. J Bacteriol. 1993;175(14):4354-63. DOI:10.1128/jb.175.14.4354-4363.1993 |
- Kwiatkowski B, Boschek B, Thiele H, and Stirm S. (1982). Endo-N-acetylneuraminidase associated with bacteriophage particles. J Virol. 1982;43(2):697-704. DOI:10.1128/JVI.43.2.697-704.1982 |
- Stummeyer K, Dickmanns A, Mühlenhoff M, Gerardy-Schahn R, and Ficner R. (2005). Crystal structure of the polysialic acid-degrading endosialidase of bacteriophage K1F. Nat Struct Mol Biol. 2005;12(1):90-6. DOI:10.1038/nsmb874 |
- Morley TJ, Willis LM, Whitfield C, Wakarchuk WW, and Withers SG. (2009). A new sialidase mechanism: bacteriophage K1F endo-sialidase is an inverting glycosidase. J Biol Chem. 2009;284(26):17404-10. DOI:10.1074/jbc.M109.003970 |
[[Category:Glycoside Hydrolase Families|GHnnn]]