Glucuronidase

β-Glucuronidase

spinqualitylabelsall models Ribbon diagram of glycosylated humanβα-glucuronidase complex with MPD(PDB code 3hn3). Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D This tutorial illustrates the quaternary structures of the human and E. coli β-glucuronidase enzyme. Function β-glucuronidase is a ubiquitous enzyme that catalyzes the hydrolysis of a glucuronide moiety from a variety of substrates. This enzyme is present throughout biological systems, including bacteria up through humans. α-glucuronidase catalyzes the conversion of α-D-glucuronoside to alcohol and D-glucuronate. Relevance Deficiencies in the human form of β-glucuronidase (overall structure, PDB ID 3HN3) is associated with a disease known as Sly Syndrome (AKA Mucopolysaccharidosis VII -- MPS VII). This disease is characterized by mental retardation, short stature, macrocephaly, and enlarged joints. As is commonly seen with genetic disorders, patients with this disease present a spectrum of symptom severity, but the disease is always ultimately fatal. The E. coli form of β-glucuronidase (overall structure, PDB ID 3LPF) is associated with the side effects seen with administration of the cancer chemotherapy drug CPT-11. This drug gets converted to SN38, a topoisomerase inhibitor, by the liver. The body adds a glucuronide group to this molecule (now SN38-G) to mark it for elimination, which partially occurs through the intestine. Once in the intestine, bacterial β-glucuronidase cleaves the glucuronide from the SN38-G, releasing the SN38 into the intestinal lumen. The released SN38 prevents cell division, compromising the epithelial lining of the intestines, a painful and dangerous side-effect of CPT-11 administration. Selective inhibition of bacterial β-glucuronidase is desired to alleviate this side-effect of CPT-11 treatment, hopefully without inhibiting the human form of the enzyme. Structural highlights The structure of E. coli β-glucuronidase contains 4 identical subunits (homotetramer). The structure of the enzyme contains both α-helix (blue) and β-sheet (yellow) forms of secondary structure, with the β-sheets arranged in β-barrels in an immunoglobulin-like fold.

3D Structures of glucuronisidase

Updated on 07-April-2015

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• α-D-glucuronidase
  • 1gqi – PcAGUS – Pseudomonas cellulosa
    
  • 1k9d, 1mqp – GsAGUS – Geobacillus stearothermophilus
    
  • 1mqr – GsAGUS (mutant)
    
  • 4c90, 4c91 – AGUS – Bacteroides ovatus
    
• α-D-glucuronidase binary complex
  • 1gqj – PcAGUS + xylobiose
    
  • 1gqk – PcAGUS + glucuronic acid
    
  • 1mqq – GsAGUS + glucuronic acid
    
  • 1k9e – GsAGUS (mutant) + methyl-glucuronic acid
    
  • 1k9f – GsAGUS (mutant) + aldotetraouronic acid
    
  • 1h41 – PcAGUS (mutant) + aldotriuronic acid
    
• α-D-glucuronidase ternary complex
  • 1gql – AGUS + glucuronic acid + xylotriose – Cellvibrio japonicus
    
  • 1l8n – GsAGUS (mutant) + methyl-glucuronic acid + xylotriose
    
• β-glucuronidase

• • 1bhg, 3hn3 – hBGUS – human
    
  • 3k46 – EcBGUS – Escherichia coli
    
  • 3k4a – EcBGUS (mutant)
    
  • 3vny – AcBGUS – Acidobacterium capsulatum
    
  • 4jkk, 4jkl – BGUS – Streptococcus agalactiae
    
• β-glucuronidase binary complex
  • 3vnz – AcBGUS + glucuronic acid
    
  • 3vo0 – AcBGUS + glucuronic acid derivative
    
  • 3k4d – EcBGUS + glucaro-D-lactam
    
  • 3lpf, 3lpg, 4jhz – EcBGUS + inhibitor
    
  • 4jkm – BGUS + MBP – Clostridium perfringens
    

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Kimberly Lane, Michal Harel, Alexander Berchansky