2OQD

Crystal Structure of BthTX-II

Summary for 2OQD

• Entry DOI: 10.2210/pdb2oqd/pdb
• Related: 1GMZ 1PAO 1U73
• Descriptor: Phospholipase A2 (2 entities in total)
• Functional Keywords: asp49-phospholipase a2, bthtx-ii, bothropstoxin ii, bothrops jararacussu, hydrolase
• Biological source: Bothrops jararacussu (jararacussu)
• Cellular location: Secreted: P45881
• Total number of polymer chains: 2
• Total formula weight: 28030.40

Authors

Correa, L.C.,Marchi-Salvador, D.P.,Cintra, A.C.O.,Soares, A.M.,Fontes, M.R.M. (deposition date: 2007-01-31, release date: 2008-02-12, Last modification date: 2024-11-20)

Primary citation

Correa, L.C.,Marchi-Salvador, D.P.,Cintra, A.C.,Sampaio, S.V.,Soares, A.M.,Fontes, M.R.
Crystal structure of a myotoxic Asp49-phospholipase A(2) with low catalytic activity: Insights into Ca(2+)-independent catalytic mechanism.
Biochim.Biophys.Acta, 1784:591-599, 2008

PubMed Abstract: A 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.

PubMed: 18261474
DOI: 10.1016/j.bbapap.2008.01.007

Experimental method

X-RAY DIFFRACTION (2.19 Å)