A neurotoxic secreted phospholipase A2, ammodytoxin, forms a high-affinity complex with calmodulin (CaM) which leads to increase of its stability and enzymatic activity. We generated energetically the most favorable model of the complex. It explains, in structural terms, all of the effects observed. Based on the proposed structure we suggested that structurally similar mammalian sPLA2s of groups V and X, but not of IB and IIA, form stable complexes with CaM, which should also result in the augmentation of their catalytic activity. By confirming the latter, the model was validated.
COBISS.SI-ID: 23512103
We developed an effective Escherichia coli expression system, together with an in vitro refolding and simple purification procedure, which yields up to 10 mg of mature human sPLA2-X from a litre of culture. In contrast to the natural protein, the recombinant enzyme was produced in bacterial cells without the N-terminal propeptide, i.e. as a mature protein, and was not N-glycosylated. It however retained all the enzymatic properties for hydrolysis of vesicular substrates composed of either phosphatidylglycerol or phosphatidylcholine.
COBISS.SI-ID: 24268839
In mammals, 29 enzymes with phospholipase A2 activity, which act intra- and/or extracellularly, have been identified. Most of the latter are secretory phospholipases A2. By their enzymatic activity or by binding to receptors, as ligands, sPLA2s play an important role in a variety of physiological and pathological processes. This has attracted the interest of pharmaceutical companies in developing sPLA2 inhibitors which could be helpful in sPLA2 related diseases, such as inflammation, atherosclerosis, neurodegeneration and cancer.
COBISS.SI-ID: 21552167
Calmodulin stabilizes the conformation of a group IIA neurotoxic secreted PLA2, ammodytoxin, and thereby restores its activity. These results provide insights not only into the neurotoxic action of ammodytoxins, but also into the mechanisms involved in the regulation of activity of structurally similar sPLA2s, such as mammalian group V and X enzymes, within the cytosol.
COBISS.SI-ID: 23138087