2oqd | pdb_00002oqd
Crystal Structure of BthTX-II
Structural highlights
Function[PA2B2_BOTJR] Snake venom phospholipase A2 (PLA2) that shows a moderate enzymatic activity. It induces indirect hemolytic, anticoagulant, and cytotoxic activities. In vivo, it induces muscle necrosis, accompanied by polymorphonuclear cell infiltration, and edema in the mouse paw. PLA2 catalyzes the calcium-dependent hydrolysis of the 2-acyl groups in 3-sn-phosphoglycerides.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedA myotoxic Asp49-phospholipase A2 (Asp49-PLA2) with low catalytic activity (BthTX-II from Bothrops jararacussu venom) was crystallized and the molecular-replacement solution has been obtained with a dimer in the asymmetric unit. The quaternary structure of BthTX-II resembles the myotoxic Asp49-PLA2 PrTX-III (piratoxin III from B. pirajai venom) and all non-catalytic and myotoxic dimeric Lys49-PLA2S. Despite of this, BthTX-II is different from the highly catalytic and non-myotoxic BthA-I (acidic PLA2 from B. jararacussu) and other Asp49-PLA2S. BthTX-II structure showed a severe distortion of calcium-binding loop leading to displacement of the C-terminal region. Tyr28 side chain, present in this region, is in an opposite position in relation to the same residue in the catalytic activity Asp49-PLA2S, making a hydrogen bond with the atom O delta 2 of the catalytically active Asp49, which should coordinate the calcium. This high distortion may also be confirmed by the inability of BthTX-II to bind Na+ ions at the Ca2+-binding loop, despite of the crystallization to have occurred in the presence of this ion. In contrast, other Asp49-PLA2S which are able to bind Ca2+ ions are also able to bind Na+ ions at this loop. The comparison with other catalytic, non-catalytic and inhibited PLA2S indicates that the BthTX-II is not able to bind calcium ions; consequently, we suggest that its low catalytic function is based on an alternative way compared with other PLA2S. Crystal structure of a myotoxic Asp49-phospholipase A2 with low catalytic activity: Insights into Ca2+-independent catalytic mechanism.,Correa LC, Marchi-Salvador DP, Cintra AC, Sampaio SV, Soares AM, Fontes MR Biochim Biophys Acta. 2008 Apr;1784(4):591-9. Epub 2008 Jan 26. PMID:18261474[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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