4fa0 | pdb_00004fa0
Crystal structure of human AdPLA to 2.65 A resolution
Structural highlights
Function[HRSL3_HUMAN] Exhibits PLA1/2 activity, catalyzing the calcium-independent hydrolysis of acyl groups in various phosphatidylcholines (PC) and phosphatidylethanolamine (PE). For most substrates, PLA1 activity is much higher than PLA2 activity. Specifically catalyzes the release of fatty acids from phospholipids in adipose tissue (By similarity). N- and O-acylation activity is hardly detectable. Might decrease protein phosphatase 2A (PP2A) activity.[1] [2] Publication Abstract from PubMedAdipose phospholipase A(2) (AdPLA or Group XVI PLA(2)) plays an important role in the onset of obesity by suppressing adipose tissue lipolysis. As a consequence, AdPLA-deficient mice are resistant to obesity induced by high-fat diet or by leptin deficiency. It has been proposed that AdPLA mediates its anti-lipolytic effects by catalyzing the release of arachidonic acid. Based on sequence homology, AdPLA is part of a small family of acyltransferases and phospholipases related to lecithin:retinol acyltransferases (LRAT). To better understand the enzymatic mechanism of AdPLA and related LRAT proteins, we solved the crystal structure of AdPLA. Our model indicates that AdPLA is structurally related to the NlpC/P60 family of cysteine proteases, having its secondary structure elements configured in a circular permutation of the classic papain fold. Using both structural and biochemical evidence we demonstrate that the enzymatic activity of AdPLA is mediated by a distinctive Cys-His-His catalytic triad and that the C-terminal transmembrane domain of AdPLA is required for the interfacial catalysis. Analysis of the enzymatic activity of AdPLA toward synthetic and natural substrates indicates that AdPLA displays PLA(1) in addition to PLA(2) activity. Thus our results provide insight into the enzymatic mechanism and biochemical properties of AdPLA and LRAT-related proteins, and lead us to propose an alternate mechanism for AdPLA in promoting adipose tissue lipolysis that is not contingent on the release of arachidonic acid and which is compatible with its combined PLA(1)/A(2) activity. Structure/Function Relationships of Adipose Phospholipase A2 Containing a Cys-His-His Catalytic Triad.,Pang XY, Cao J, Addington L, Lovell S, Battaile KP, Zhang N, Rao JL, Dennis EA, Moise AR J Biol Chem. 2012 Aug 25. PMID:22923616[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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