Isoform-specific membrane insertion of secretory phospholipase A2 and functional implications
Abhay H Pande1, Shan Qin, Kathleen N Nemec
1Biomolecular Science Center, University of Central Florida, Orlando, Florida 32826, USA.
Biochemistry
|October 13, 2006
Summary
Phospholipase A(2) (PLA(2)) membrane insertion is crucial for enzyme function. Group IB and IIA PLA(2)s insert into membranes, dependent on fluidity, unlike diverse group III PLA(2)s.
Area of Science:
- Biochemistry
- Enzymology
- Membrane Biology
Background:
- Membrane insertion depth is vital for interfacial enzyme function.
- Systematic studies on phospholipase A(2) (PLA(2)) membrane insertion are lacking.
Purpose of the Study:
- To investigate and compare the membrane insertion of human group IB PLA(2) (hIBPLA(2)) with V3W-hIIAPLA(2) and bee venom PLA(2) (bvPLA(2)).
- To determine the role of membrane properties like fluidity and charge on PLA(2) activity and insertion.
Main Methods:
- Utilized tryptophan fluorescence quenching with varying membrane compositions (fluid vs. solid, anionic charge).
- Assessed enzyme activity in response to altered membrane properties.
Main Results:
- hIBPLA(2) insertion is enhanced by anionic membrane charge and increased fluidity, correlating with higher activity.
- Trp(3) of hIBPLA(2) and V3W-hIIAPLA(2) significantly penetrate fluid membranes, while bvPLA(2) shows no tryptophan insertion.
- Membrane fluidity controls hIBPLA(2) insertion and is necessary for its full activity.
Conclusions:
- Structurally similar group IB and IIA PLA(2)s significantly penetrate membranes, unlike diverse group III PLA(2)s.
- Membrane insertion, controlled by fluidity, facilitates the activation of IB and IIA PLA(2)s.
- Distinct PLA(2) isoforms may use different strategies for substrate access and product release.
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