Title

Functional insight for β-glucuronidase in Escherichia coli and Staphylococcus sp. RLH1

Authors

Loganathan Arul^1, *, George Benita¹ and Ponnusamy Balasubramanian¹

Affiliation

¹Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore - 641 003, India

Email

arulsrj@rediffmail.com

Phone

91 422 6611353; * Corresponding author

Article Type

Hypothesis

Date

received March 04, 2008; revised April 24, 2008; accepted May 05, 2008; published May 22, 2008

Abstract

Glycosyl hydrolases hydrolyze the glycosidic bond either in carbohydrates or between carbohydrate and non-carbohydrate moiety. The β-glucuronidase (beta D-glucuronoside glucuronosohydrolase; EC 3.2.1.31) enzyme belongs to the family-2 glycosyl hydrolase. The E. coli borne β-glucuronidase gene (uidA) was devised as a gene fusion marker in plant genetic transformation experiments. Recent plant transformation vectors contain a novel β-glucuronidase (gusA) derived from Staphylococcus sp. RLH1 for E. coli uidA. It is known to have a ten fold higher sensitivity compared to E. coli β-glucuronidase. The functional superiority of Staphylococcus (gusA) over E. coli (uidA) activity is not fully known. The comparison of secondary structural elements among them revealed an increased percentage of random coils in Staphylococcus β-glucuronidase. The 3D model of gusA shows catalytic site residues 396Glu, 508Glu and 471Tyr of gusA in loop regions. Accessible surface area (ASA) calculations on the 3D model showed increased ASA for active site residues in Staphylococcus β-glucuronidase. Increased random coil, the presence of catalytic residues in loops, greater solvent accessibility of active residues and increased charged residues in gusA of Staphylococcus might facilitate interaction with the solvent. This hypothesizes the enhanced catalytic activity of β-glucuronidase in Staphylococcus sp. RLH1 compared to that in E. coli.

Keywords

β-glucuronidase; structure-function relationships; uidA; GUSPlus; catalytic activity

Citation

Arul et al., Bioinformation 2(8): 339-343 (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.