Glycoside Hydrolase Family 29

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• Author: ^^^Gerlind Suzlenbacher^^^
• Responsible Curator: ^^^Steve Withers^^^

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Glycoside Hydrolase Family GH 29
Clan	none
Mechanism	retaining
Active site residues	known
CAZy DB link
http://www.cazy.org/fam/GH29.html

Substrate specificities

The glycoside hydrolases of this family are exo-acting α-fucosidases from archaeal, bacterial and eukaryotic origin. No other activities have been observed for GH29 family members. So fare the only other CAZY family containing α-fucosidases is family GH95. The human enzyme FucA1 is of medical interest because its deficiency leads to fucosidosis, an autosomal recessive lysosomal storage disease [1].

Kinetics and Mechanism

GH29 α-fucosidases are retaining enzymes following a classical Koshland double-displacement mechanism, as first proposed in 1987 for human liver α-fucosidase via burst kinetics experiments and using methanol as an alternative glycone acceptor to produce methyl-α-L-fucoside [2]. This has been further confirmed by ¹H NMR monitoring of the reaction catalyzed by a α-L-fucosidase from Thermus sp. [3], and a α-L-fucosidase from the marine mollusc Pecten maximus[4], as well as by COSY and ¹H-¹³C NMR spectroscopy analysis of the interglycosidic linkage of disaccharides formed by the transglycosylation action of Sulfolobus solfataricus α-L-fucosidase, Ssα-fuc [5]. GH95 α-fucosidases, in contrast, operate with inversion of the anomeric configuration.

Catalytic Residues

The catalytic nucleophile in GH29 was first identified in the Sulfolobus solfataricus α-L-fucosidase, Ssα-fuc, as Asp242 in the sequence VYFDWWI via chemical rescue of an inactive mutant with sodium azide [6]. Concomitantly the catalytic nucleophile of Thermotoga maritima α-L-fucosidase, Tmα-fuc, was confirmed to be Asp224 in the sequence LWNDMGW through trapping of the 2-deoxy-2-fluorofucosyl-enzyme intermediate and subsequent peptide mapping via LC-MS/MS technologies, as well as by chemical rescue of an inactive mutant [7]. The trapping of the 2-deoxy-2-fluorofucosyl-enzyme intermediate in Tmα-fuc was corroborated by crystallographic studies [8]. The catalytic nucleophile of the human enzyme FucA1 has recently been identified as being Asp225 [9].

Whereas the catalytic nucleophile in GH29 has been shown to be a conserved aspartate residue, the identity of the general acid/base is still controversial. Structural and mutagenesis studies of Tmα-fuc provided strong evidence for the variant Glu266 being the general acid/base [8]. In the crystal structure the carboxyl function of this residue is 5.5 Å apart from that of the catalytic nucleophile Asp224, a distance commonly observed in retaining glycosidases proceeding via a classical Koshland double-displacement mechanism. Although multiple sequence alignments show that Glu266 is not conserved within GH29, the residue is structurally conserved in two 3-D structures of α-L-fucosidases from Bacteroides thetaiotaomicron sp., recently deposited in the Protein Data Bank (accession numbers 3eyp and 3gza). Studies of Ssα-fuc demonstrated that mutation of the Glu residue corresponding in sequence to Tmα-fuc Glu266 scarcely impaired the catalytic activity of the enzyme, whereas the E58G mutant yielded a 4000-fold reduction of kcat/K_M and could be chemically rescued [10]. In the crystal structure of Tmα-fuc in complex with fucose [8], the residue corresponding to Ssa-fuc Glu58, Glu66, is found 7.5 Å distant form the catalytic nucleophile Asp224 and hydrogen bond to the C-3 hydroxyl group of fucose, which altogether makes this residue an unlikely candidate for the function of the general acid/base. Normal.dotm 0 0 1 32 187 AFMB 1 1 229 12.0 0 false 21 18 pt 18 pt 0 0 false false false A recent study of the human α-L-fucosidase FucA1, carefully done combining bioinformatics, structural modeling, mutagenesis, chemical rescue with azide and 1H NMR spectral analysis, identified Glu289 as the general acid/base.

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 [11].

First catalytic nucleophile identification

Cite some reference here, with a short (1-2 sentence) explanation [12].

First general acid/base residue identification

Cite some reference here, with a short (1-2 sentence) explanation [13].

First 3-D structure

Cite some reference here, with a short (1-2 sentence) explanation [3].

References

1. O'Brien JS, Willems PJ, Fukushima H, de Wet JR, Darby JK, Di Cioccio R, Fowler ML, and Shows TB. (1987). Molecular biology of the alpha-L-fucosidase gene and fucosidosis. Enzyme. 1987;38(1-4):45-53. DOI:10.1159/000469189 |
2. White WJ Jr, Schray KJ, Legler G, and Alhadeff JA. (1987). Further studies on the catalytic mechanism of human liver alpha-L-fucosidase. Biochim Biophys Acta. 1987;912(1):132-8. DOI:10.1016/0167-4838(87)90256-1 |
3. Eneyskaya EV, Kulminskaya AA, Kalkkinen N, Nifantiev NE, Arbatskii NP, Saenko AI, Chepurnaya OV, Arutyunyan AV, Shabalin KA, and Neustroev KN. (2001). An alpha-L-fucosidase from Thermus sp. with unusually broad specificity. Glycoconj J. 2001;18(10):827-34. DOI:10.1023/a:1021163720282 |
4. Berteau O, McCort I, Goasdoué N, Tissot B, and Daniel R. (2002). Characterization of a new alpha-L-fucosidase isolated from the marine mollusk Pecten maximus that catalyzes the hydrolysis of alpha-L-fucose from algal fucoidan (Ascophyllum nodosum). Glycobiology. 2002;12(4):273-82. DOI:10.1093/glycob/12.4.273 |
5. Cobucci-Ponzano B, Trincone A, Giordano A, Rossi M, and Moracci M. (2003). Identification of an archaeal alpha-L-fucosidase encoded by an interrupted gene. Production of a functional enzyme by mutations mimicking programmed -1 frameshifting. J Biol Chem. 2003;278(17):14622-31. DOI:10.1074/jbc.M211834200 |
6. Cobucci-Ponzano B, Trincone A, Giordano A, Rossi M, and Moracci M. (2003). Identification of the catalytic nucleophile of the family 29 alpha-L-fucosidase from Sulfolobus solfataricus via chemical rescue of an inactive mutant. Biochemistry. 2003;42(32):9525-31. DOI:10.1021/bi035036t |
7. Tarling CA, He S, Sulzenbacher G, Bignon C, Bourne Y, Henrissat B, and Withers SG. (2003). Identification of the catalytic nucleophile of the family 29 alpha-L-fucosidase from Thermotoga maritima through trapping of a covalent glycosyl-enzyme intermediate and mutagenesis. J Biol Chem. 2003;278(48):47394-9. DOI:10.1074/jbc.M306610200 |
8. Sulzenbacher G, Bignon C, Nishimura T, Tarling CA, Withers SG, Henrissat B, and Bourne Y. (2004). Crystal structure of Thermotoga maritima alpha-L-fucosidase. Insights into the catalytic mechanism and the molecular basis for fucosidosis. J Biol Chem. 2004;279(13):13119-28. DOI:10.1074/jbc.M313783200 |
9. Liu SW, Chen CS, Chang SS, Mong KK, Lin CH, Chang CW, Tang CY, and Li YK. (2009). Identification of essential residues of human alpha-L-fucosidase and tests of its mechanism. Biochemistry. 2009;48(1):110-20. DOI:10.1021/bi801529t |
10. Cobucci-Ponzano B, Mazzone M, Rossi M, and Moracci M. (2005). Probing the catalytically essential residues of the alpha-L-fucosidase from the hyperthermophilic archaeon Sulfolobus solfataricus. Biochemistry. 2005;44(16):6331-42. DOI:10.1021/bi047495f |