Title

β-glucuronidase of family-2 glycosyl hydrolase: A missing member in plants

Authors

Loganathan Arul, George Benita, Duraialagaraja Sudhakar, Balsamy Thayumanavan and Ponnusamy Balasubramanian

Affiliation

Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore 641003, India

Email

arulsra@gmail.com; * Corresponding author

Article Type

Hypothesis

Date

received November 25, 2008; accepted December 01, 2008; published December 31, 2008

Abstract

Glycosyl hydrolases hydrolyze the glycosidic bond in carbohydrates or between a carbohydrate and a non-carbohydrate moiety. β - glucuronidase (GUS) is classified under two glycosyl hydrolase families (2 and 79) and the family-2 β-glucuronidase is reported in a wide range of organisms, but not in plants. The family-79 endo-β-glucuronidase (heparanase) is reported in microorganisms, vertebrates and plants. The E. coli family-2 β-glucuronidase (uidA) had been successfully devised as a reporter gene in plant transformation on the basis that plants do not have homologous GUS activity. On the contrary, histochemical staining with X-Gluc was reported in wild type (non-transgenic) plants. Data shows that, family-2 β-glucuronidase homologous sequence is not found in plants. Further, β-glucuronidases of family-2 and 79 lack appreciable sequence similarity. However, the catalytic site residues, glutamic acid and tyrosine of the family-2 β-glucuronidase are found to be conserved in family-79 β-glucuronidase of plants. This led to propose that the GUS staining reported in wild type plants is largely because of the broad substrate specificity of family-79 β-glucuronidase on X-Gluc and not due to the family-2 β-glucuronidase, as the latter has been found to be missing in plants.

Keywords

glycosyl hydrolase; β-glucuronidase; heparanase; endogenous GUS activity

Citation

Loganathan et al., Bioinformation 3(5): 194-197 (2008)

Edited by

P. Kangueane

ISSN

0973-2063

Publisher

Biomedical Informatics

License

This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. This is distributed under the terms of the Creative Commons Attribution License.