1. Identification and characterization of two new types of bacterial L-serine dehydratases and assessment of the function of the ACT domain.
- Author
-
Xu XL and Grant GA
- Subjects
- Amino Acid Sequence, Bacillaceae genetics, Bacteroidetes genetics, Cations, Monovalent pharmacology, Databases, Protein, Enzyme Activation drug effects, Kinetics, L-Serine Dehydratase genetics, L-Serine Dehydratase isolation & purification, Molecular Sequence Data, Oxygen pharmacology, Protein Structure, Tertiary, Species Specificity, Bacillaceae enzymology, Bacteroidetes enzymology, L-Serine Dehydratase chemistry, L-Serine Dehydratase metabolism
- Abstract
Two new types of bacterial Fe-S L-serine dehydratases have been identified. These join two previously recognized enzyme types, for a total of four, that are distinguished on the basis of domain arrangement and amino acid sequence. A Type 3 enzyme from Amphibacillus xylanus (axLSD) and a Type 4 enzyme from Heliscomenobacter hydrossis (hhLSD) were cloned, expressed, purified, and characterized. Like the Type 1 enzyme from Bacillus subtilis (bsLSD), axLSD required a monovalent cation, preferably potassium, for activity. However, the hhLSD was without activity even after reconstitution of the iron-sulfur center by a process that successfully restored activity to oxygen-inactivated axLSD. This and other characteristics suggest that this Type 4 protein may be a pseudoenzyme. The oxygen sensitivity of axLSD was greater than other L-serine dehydratases so far studied and suggested that there may be significant conformational differences among the four types resulting in widely different solvent accessibility of the Fe-S clusters in these enzymes. The role of the ACT domain in these enzymes was explored by deleting it from bsLSD. Although there was an effect on the kinetic parameters, this domain was not responsible for the cation requirement nor did its removal have a significant effect on oxygen sensitivity., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF