Substrate interferes with dimerisation of outer membrane phospholipase A.
Outer membrane phospholipase A (OMPLA) activity is regulated by reversible dimerisation with the dimer being the active species. Observed lag phases in activity indicated that dimerisation may be slow relative to turnover. A covalent OMPLA dimer indeed did not display lag phase behaviour. A model for OMPLA kinetics was proposed accounting for a slow dimerisation step. Preincubation conditions determined the initial amount of monomer and influenced both lag times and final activities. Under the conditions used, substrate concentrations higher than 50 mol% inhibited OMPLA activity and increased lag times. Our results may shed more light on mechanisms controlling OMPLA activity in vivo.
Kingma
Roelie L
RL
Department of Membrane Enzymology, Centre for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
Egmond
Maarten R
MR
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D002384:Catalysis; D019281:Dimerization; D007700:Kinetics; D008244:Lysophosphatidylcholines; D008954:Models, Biological; D010741:Phospholipases A / Q000737:chemistry* / Q000378:metabolism*; D054466:Phospholipases A1; D020836:Protein Structure, Quaternary; D013379:Substrate Specificity
D001425:Bacterial Outer Membrane Proteins; D008244:Lysophosphatidylcholines; C019574:thioglycollecithin; D010741:Phospholipases A; D054466:Phospholipases A1; C412876:outer membrane phospholipase A