1giq: Difference between revisions
New page: left|200px<br /><applet load="1giq" size="450" color="white" frame="true" align="right" spinBox="true" caption="1giq, resolution 1.80Å" /> '''CRYSTAL STRUCTURE OF... |
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[[Image:1giq.jpg|left|200px]]<br /><applet load="1giq" size=" | [[Image:1giq.jpg|left|200px]]<br /><applet load="1giq" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1giq, resolution 1.80Å" /> | caption="1giq, resolution 1.80Å" /> | ||
'''CRYSTAL STRUCTURE OF THE ENZYMATIC COMPONET OF IOTA-TOXIN FROM CLOSTRIDIUM PERFRINGENS WITH NADH'''<br /> | '''CRYSTAL STRUCTURE OF THE ENZYMATIC COMPONET OF IOTA-TOXIN FROM CLOSTRIDIUM PERFRINGENS WITH NADH'''<br /> | ||
==Overview== | ==Overview== | ||
Iota-toxin from Clostridium perfringens type E is an ADP-ribosylating | Iota-toxin from Clostridium perfringens type E is an ADP-ribosylating toxin (ADPRT) that ADP-ribosylates actin, which is lethal and dermonecrotic in mammals. It is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). Ia ADP-ribosylates G-actin at arginine 177, resulting in the depolymerization of the actin cytoskeleton. Here, we report on studies of the structure-function relationship by the crystal structures of Ia complexed with NADH and NADPH (at 1.8 A and 2.1 A resolution, respectively) and mutagenesis that map the active residues. The catalytic C-domain structure was similar to that of Bacillus cereus vegetative insecticidal protein (VIP2), which is an insect-targeted toxin, except for the EXE loop region. However, a significant structural difference could be seen in the N-domain, which interacts with Ib, suggesting an evolutionary difference between mammalian-targeted and insect-targeted ADPRT. The high resolution structure analysis revealed specific NAD conformation (a ring-like conformation of nicotinamide mononucleotide (NMN)) supported by Arg295, Arg296, Asn335, Arg352 and Glu380. Additionally, the mutagenesis study showed that the residues Tyr251, Arg295, Glu301, Ser338, Phe349, Arg352 and Glu380, including a newly identified one, are essential for NAD(+)-glycohydrolase (NADase) activity. At least one residue, Glu378, is an essential residue for ADP-ribosyltransferase (ARTase), but not for NADase. Consequently, the structural feature and these mutagenesis findings suggest that the catalytic mechanism of Ia proceeds via an Sn1-type reaction. | ||
==About this Structure== | ==About this Structure== | ||
1GIQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_perfringens Clostridium perfringens] with NAD as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | 1GIQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_perfringens Clostridium perfringens] with <scene name='pdbligand=NAD:'>NAD</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GIQ OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: enzymatic component]] | [[Category: enzymatic component]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:50:55 2008'' | ||
Revision as of 13:51, 21 February 2008
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CRYSTAL STRUCTURE OF THE ENZYMATIC COMPONET OF IOTA-TOXIN FROM CLOSTRIDIUM PERFRINGENS WITH NADH
OverviewOverview
Iota-toxin from Clostridium perfringens type E is an ADP-ribosylating toxin (ADPRT) that ADP-ribosylates actin, which is lethal and dermonecrotic in mammals. It is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). Ia ADP-ribosylates G-actin at arginine 177, resulting in the depolymerization of the actin cytoskeleton. Here, we report on studies of the structure-function relationship by the crystal structures of Ia complexed with NADH and NADPH (at 1.8 A and 2.1 A resolution, respectively) and mutagenesis that map the active residues. The catalytic C-domain structure was similar to that of Bacillus cereus vegetative insecticidal protein (VIP2), which is an insect-targeted toxin, except for the EXE loop region. However, a significant structural difference could be seen in the N-domain, which interacts with Ib, suggesting an evolutionary difference between mammalian-targeted and insect-targeted ADPRT. The high resolution structure analysis revealed specific NAD conformation (a ring-like conformation of nicotinamide mononucleotide (NMN)) supported by Arg295, Arg296, Asn335, Arg352 and Glu380. Additionally, the mutagenesis study showed that the residues Tyr251, Arg295, Glu301, Ser338, Phe349, Arg352 and Glu380, including a newly identified one, are essential for NAD(+)-glycohydrolase (NADase) activity. At least one residue, Glu378, is an essential residue for ADP-ribosyltransferase (ARTase), but not for NADase. Consequently, the structural feature and these mutagenesis findings suggest that the catalytic mechanism of Ia proceeds via an Sn1-type reaction.
About this StructureAbout this Structure
1GIQ is a Single protein structure of sequence from Clostridium perfringens with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure and site-directed mutagenesis of enzymatic components from Clostridium perfringens iota-toxin., Tsuge H, Nagahama M, Nishimura H, Hisatsune J, Sakaguchi Y, Itogawa Y, Katunuma N, Sakurai J, J Mol Biol. 2003 Jan 17;325(3):471-83. PMID:12498797
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