Glycosyltransferase Family 138

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• Author: Wei Peng
• Responsible Curator: Kim Orth

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Glycosyltransferase Family GT138
Clan	Fido fold
Mechanism	Inverting
Active site residues	Known
CAZy DB link
https://www.cazy.org/GT138.html

Substrate specificities

GT138 family of glycosyltransferase is exemplified by AvrB [1] that contains a Fido domain [2] (Fig. 1A). AvrB is different from other known glycosyltransferases containing folds of GT-A, GT-B, GT-C, lysozyme-type, GT101, and GT108 (Fig. 1B). Interestingly, Fido proteins can also be enzymes with activities of AMPylation [3], phosphorylation [4], UMPylation [5], and phosphocholination [6, 7]. Therefore, AvrB is a unique Fido protein that functions as a glycosyltransferase. As a bacterial effector from the plant pathogen Pseudomonas syringae, AvrB utilizes host UDP-rhamnose (or dTDP-rhamnose in vitro) as a co-substrate to modify the host protein RIN4 and causes the programmed cell death (namely hypersensitive response).

Figure 1. Glycosyltransferase folds. (A) Fido fold (left) is found in diverse enzymes including AvrB (right), which is a distinct glycosyltransferase. (B) Other known glycosyltransferases contain folds of GT-A, GT-B, GT-C, lysozyme-type, GT101, and GT108. PDB codes are provided for representative structures.

Kinetics and Mechanism

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Catalytic Residues

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Three-dimensional structures

Fido glycosyltransferase structures are represented by AvrB. AvrB contains a relatively large internal domain between helix α2 and helix α3 (Fig. 1A).

Family Firsts

First stereochemistry determination

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First catalytic nucleophile identification

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First general acid/base residue identification

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First 3-D structure

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References

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1. Peng W, Garcia N, Servage KA, Kohler JJ, Ready JM, Tomchick DR, Fernandez J, and Orth K. (2024). Pseudomonas effector AvrB is a glycosyltransferase that rhamnosylates plant guardee protein RIN4. Sci Adv. 2024;10(7):eadd5108. DOI:10.1126/sciadv.add5108 |
2. Kinch LN, Yarbrough ML, Orth K, and Grishin NV. (2009). Fido, a novel AMPylation domain common to fic, doc, and AvrB. PLoS One. 2009;4(6):e5818. DOI:10.1371/journal.pone.0005818 |