Glycoside hydrolase family 28 explained

Symbol:	Glyco_hydro_28
Glycosyl hydrolases family 28
Pfam:	PF00295
Pfam Clan:	CL0268
Interpro:	IPR000743
Prosite:	PDOC00415
Scop:	1rmg
Cazy:	GH28
Membranome Superfamily:	73

In molecular biology, glycoside hydrolase family 28 is a family of glycoside hydrolases, which are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families.^{[1] [2] [3]} This classification is available on the CAZy web site,^{[4] [5]} and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes.^{[6] [7]}

Glycoside hydrolase family 28 CAZY GH_28 comprises enzymes with several known activities; polygalacturonase ; exo-polygalacturonase ; exo-polygalacturonase ; rhamnogalacturonase (EC not defined).

Polygalacturonase (PG) (pectinase)^{[8] [9]} catalyzes the random hydrolysis of 1,4-alpha-D-galactosiduronic linkages in pectate and other galacturonans. In fruit, polygalacturonase plays an important role in cell wall metabolism during ripening. In plant bacterial pathogens such as Erwinia carotovora or Ralstonia solanacearum (Pseudomonas solanacearum) and fungal pathogens such as Aspergillus niger, polygalacturonase is involved in maceration and soft-rotting of plant tissue. Exo-poly-alpha-D-galacturonosidase (exoPG)^[10] hydrolyzes peptic acid from the non-reducing end, releasing digalacturonate. PG and exoPG share a few regions of sequence similarity, and belong to family 28 of the glycosyl hydrolases.

Notes and References

1. Henrissat B, Callebaut I, Fabrega S, Lehn P, Mornon JP, Davies G . Conserved catalytic machinery and the prediction of a common fold for several families of glycosyl hydrolases . Proceedings of the National Academy of Sciences of the United States of America . 92 . 15 . 7090–4 . July 1995 . 7624375 . 41477 . 10.1073/pnas.92.15.7090 . 1995PNAS...92.7090H . free .
2. Davies G, Henrissat B . Structures and mechanisms of glycosyl hydrolases . Structure . 3 . 9 . 853–9 . September 1995 . 8535779 . 10.1016/S0969-2126(01)00220-9 . free .
3. Henrissat B, Bairoch A . Updating the sequence-based classification of glycosyl hydrolases . The Biochemical Journal . 316 . Pt 2 . 695–6 . June 1996 . 8687420 . 1217404 . 10.1042/bj3160695.
4. Web site: Home. CAZy.org. en. 2018-03-06.
5. Lombard V, Golaconda Ramulu H, Drula E, Coutinho PM, Henrissat B . The carbohydrate-active enzymes database (CAZy) in 2013 . Nucleic Acids Research . 42 . Database issue . D490-5 . January 2014 . 24270786 . 10.1093/nar/gkt1178 . 3965031 .
6. Web site: Glycoside Hydrolase Family 28. CAZypedia.org. en. 2018-03-06.
7. Ten years of CAZypedia: a living encyclopedia of carbohydrate-active enzymes . Glycobiology . 28 . 1 . 3–8 . December 2018 . 29040563 . 10.1093/glycob/cwx089 . CAZypedia Consortium . free .
8. Ruttkowski E, Labitzke R, Khanh NQ, Löffler F, Gottschalk M, Jany KD . Cloning and DNA sequence analysis of a polygalacturonase cDNA from Aspergillus niger RH5344 . Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression . 1087 . 1 . 104–6 . September 1990 . 2400785 . 10.1016/0167-4781(90)90130-t .
9. Huang JH, Schell MA . DNA sequence analysis of pglA and mechanism of export of its polygalacturonase product from Pseudomonas solanacearum . Journal of Bacteriology . 172 . 7 . 3879–87 . July 1990 . 2193922 . 213369 . 10.1128/jb.172.7.3879-3887.1990.
10. He SY, Collmer A . Molecular cloning, nucleotide sequence, and marker exchange mutagenesis of the exo-poly-alpha-D-galacturonosidase-encoding pehX gene of Erwinia chrysanthemi EC16 . Journal of Bacteriology . 172 . 9 . 4988–95 . September 1990 . 2168372 . 213154 . 10.1128/jb.172.9.4988-4995.1990.