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Updated: Aug 13, 2026
11:01
Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
Published on: November 23, 2016
Summary
Bacillus subtilis p-Aminobenzoate (PABA) synthase is a two-subunit enzyme. Subunit A provides aminase activity, while subunit X enables amidotransferase activity, forming a functional PABA synthase complex.
Area of Science:
- Biochemistry
- Enzymology
- Microbial Metabolism
Background:
- p-Aminobenzoate (PABA) is a crucial precursor for folate synthesis in bacteria.
- Bacillus subtilis possesses a PABA synthase enzyme essential for its growth and survival.
Purpose of the Study:
- To characterize the enzymatic properties and subunit composition of p-Aminobenzoate (PABA) synthase from Bacillus subtilis.
- To elucidate the roles of individual subunits in the catalytic activity of PABA synthase.
Main Methods:
- Enzyme activity assays using crude extracts and fractionated enzyme preparations.
- Investigating substrate specificity and cofactor requirements (Mg2+, guanosine derivatives).
- Subunit analysis via molecular weight estimation and mutational studies (pabA locus).
Main Results:
- PABA synthase exhibits both amidotransferase (higher activity) and aminase activities.
- The enzyme requires Mg2+ and guanosine or its phosphorylated forms for optimal activity after fractionation.
- PABA synthase comprises two non-identical subunits (A: 31,000 Da, X: 19,000 Da); subunit A has aminase activity, while subunit X enables glutamine utilization for amidotransferase activity.
Conclusions:
- Bacillus subtilis PABA synthase is a hetero-oligomeric enzyme composed of subunits A and X.
- Subunit X is essential for the amidotransferase function, likely by facilitating glutamine binding or activation.
- The distinct roles of subunits A and X highlight the complex regulation of PABA biosynthesis in Bacillus subtilis.
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