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The family of bacterial ADP-ribosylating exotoxins
1Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226.
Abstract:
Pathogenic bacteria utilize a variety of virulence factors that contribute to the clinical manifestation of their pathogenesis. Bacterial ADP-ribosylating exotoxins (bAREs) represent one family of virulence factors that exert their toxic effects by transferring the ADP-ribose moiety of NAD onto specific eucaryotic target proteins. The observations that some bAREs ADP-ribosylate eucaryotic proteins that regulate signal transduction, like the heterotrimeric GTP-binding proteins and the low-molecular-weight GTP-binding proteins, has extended interest in bAREs beyond the bacteriology laboratory. Molecular studies have shown that bAREs possess little primary amino acid homology and have diverse quaternary structure-function organization. Underlying this apparent diversity, biochemical and crystallographic studies have shown that several bAREs have conserved active-site structures and possess a conserved glutamic acid within their active sites.
Insights
Bacterial ADP-ribosylating exotoxins (bAREs) are virulence factors that modify host proteins. Despite structural diversity, conserved active sites and a key glutamic acid are crucial for their function.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Pathogenic bacteria employ virulence factors for disease.
- Bacterial ADP-ribosylating exotoxins (bAREs) are a class of virulence factors.
- bAREs modify eukaryotic proteins, impacting host cell functions like signal transduction.
Purpose of the Study:
- To investigate the conserved structural and biochemical features of bacterial ADP-ribosylating exotoxins.
- To understand the underlying mechanisms of bAREs' diverse structures and functions.
Main Methods:
- Molecular studies to analyze primary amino acid homology.
- Biochemical studies to investigate enzyme activity and structure-function relationships.
- Crystallographic studies to determine high-resolution active site structures.
Main Results:
- bAREs exhibit limited primary amino acid homology and diverse quaternary structures.
- Biochemical and crystallographic analyses reveal conserved active-site structures across different bAREs.
- A conserved glutamic acid residue is identified within the active sites of several bAREs.
Conclusions:
- Despite apparent diversity, bAREs share conserved active-site architectures.
- The conserved glutamic acid is likely critical for the catalytic activity of bAREs.
- Understanding these conserved features can inform strategies against bacterial pathogenesis.