Insecticidal delta-endotoxin Cyt2Ba from Bacillus thuringiensis: Difference between revisions
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Cyt2Ba shares only 16% sequence identity to VVA2 ([[1pp0]]), nevertheless they both adopt a cytolysin fold and their structure is very similar (see their <scene name='Cyt2Ba/Cyt2ba_vva/2'>structural alignment</scene>). | Cyt2Ba shares only 16% sequence identity to VVA2 ([[1pp0]]), nevertheless they both adopt a cytolysin fold and their structure is very similar (see their <scene name='Cyt2Ba/Cyt2ba_vva/2'>structural alignment</scene>). | ||
A striking similarity is observed between the structures of the endogenously cleaved Cyt2Ba <scene name='Cyt2Ba/Cyt2ba_monomer/1'>monomer</scene> (gray) and the <scene name='Cyt2Ba/Alignment/1'>corresponding region</scene> within the inactive protoxin <scene name='Cyt2Ba/ | A striking similarity is observed between the structures of the endogenously cleaved Cyt2Ba <scene name='Cyt2Ba/Cyt2ba_monomer/1'>monomer</scene> (gray) and the <scene name='Cyt2Ba/Alignment/1'>corresponding region</scene> within the inactive protoxin <scene name='Cyt2Ba/Dimer/1'>dimer</scene> of Cyt2Aa (monomers A and B of Cyt2Aa shown red and blue, respectively, the N- and C-termini are shown in spacefill representation). Each monomer of Cyt2Aa ([[1cby]]), consists of an extra β-strand at its N-terminus and α-helix at its C-terminus compared to the cleaved Cyt2Ba. The <scene name='Cyt2Ba/Dimer_mesh/7'>dimer interface</scene> of Cyt2Aa is held together by the intertwined N-terminal strands from both monomers. The cleavage of Cyt2Aa removes the <scene name='Cyt2Ba/Dimer_mesh/9'>N and C termini segments</scene>, thereby preventing dimer formation and hence releasing a <scene name='Cyt2Ba/Monomer_toxin/2'>monomer active toxin</scene>. Similarly, it was shown that in Cyt2Ba the proteolysis causes the removal of 34 amino acids at its N-terminal and 28 or 30 residues at its C-terminus forming the crystallized toxic monomer. | ||
===Conclusions=== | ===Conclusions=== |