1dcn: Difference between revisions
New page: left|200px<br /><applet load="1dcn" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dcn, resolution 2.30Å" /> '''INACTIVE MUTANT H162... |
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[[Image:1dcn.gif|left|200px]]<br /><applet load="1dcn" size=" | [[Image:1dcn.gif|left|200px]]<br /><applet load="1dcn" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1dcn, resolution 2.30Å" /> | caption="1dcn, resolution 2.30Å" /> | ||
'''INACTIVE MUTANT H162N OF DELTA 2 CRYSTALLIN WITH BOUND ARGININOSUCCINATE'''<br /> | '''INACTIVE MUTANT H162N OF DELTA 2 CRYSTALLIN WITH BOUND ARGININOSUCCINATE'''<br /> | ||
==Overview== | ==Overview== | ||
Delta-crystallin, the major soluble protein component of avian and | Delta-crystallin, the major soluble protein component of avian and reptilian eye lenses, is highly homologous to the urea cycle enzyme, argininosuccinate lyase (ASL). In duck lenses, there are two highly homologous delta crystallins, delta I and delta II, that are 94% identical in amino acid sequence. While delta II crystallin has been shown to exhibit ASL activity in vitro, delta I is enzymatically inactive. The X-ray structure of a His to Asn mutant of duck delta II crystallin (H162N) with bound argininosuccinate has been determined to 2.3 A resolution using the molecular replacement technique. The overall fold of the protein is similar to other members of the superfamily to which this protein belongs, with the active site located in a cleft formed by three different monomers in the tetramer. The active site of the H162N mutant structure reveals that the side chain of Glu 296 has a different orientation relative to the homologous residue in the H91N mutant structure [Abu-Abed et al. (1997) Biochemistry 36, 14012-14022]. This shift results in the loss of the hydrogen bond between His 162 and Glu 296 seen in the H91N and turkey delta I crystallin structures; this H-bond is believed to be crucial for the catalytic mechanism of ASL/delta II crystallin. Argininosuccinate was found to be bound to residues in each of the three monomers that form the active site. The fumarate moiety is oriented toward active site residues His 162 and Glu 296 and other residues that are part of two of the three highly conserved regions of amino acid sequence in the superfamily, while the arginine moiety of the substrate is oriented toward residues which belong to either domain 1 or domain 2. The analysis of the structure reveals that significant conformational changes occur on substrate binding. The comparison of this structure with the inactive turkey delta I crystallin reveals that the conformation of domain 1 is crucial for substrate affinity and that the delta I protein is almost certainly inactive because it can no longer bind the substrate. | ||
==About this Structure== | ==About this Structure== | ||
1DCN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Anas_platyrhynchos Anas platyrhynchos] with AS1 as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Argininosuccinate_lyase Argininosuccinate lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.3.2.1 4.3.2.1] Full crystallographic information is available from [http:// | 1DCN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Anas_platyrhynchos Anas platyrhynchos] with <scene name='pdbligand=AS1:'>AS1</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Argininosuccinate_lyase Argininosuccinate lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.3.2.1 4.3.2.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DCN OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Argininosuccinate lyase]] | [[Category: Argininosuccinate lyase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Howell, P | [[Category: Howell, P L.]] | ||
[[Category: Lindley, P.]] | [[Category: Lindley, P.]] | ||
[[Category: Turner, M | [[Category: Turner, M A.]] | ||
[[Category: Vallee, F.]] | [[Category: Vallee, F.]] | ||
[[Category: AS1]] | [[Category: AS1]] | ||
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[[Category: eye lens protein]] | [[Category: eye lens protein]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:15:19 2008'' | ||
Revision as of 13:15, 21 February 2008
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INACTIVE MUTANT H162N OF DELTA 2 CRYSTALLIN WITH BOUND ARGININOSUCCINATE
OverviewOverview
Delta-crystallin, the major soluble protein component of avian and reptilian eye lenses, is highly homologous to the urea cycle enzyme, argininosuccinate lyase (ASL). In duck lenses, there are two highly homologous delta crystallins, delta I and delta II, that are 94% identical in amino acid sequence. While delta II crystallin has been shown to exhibit ASL activity in vitro, delta I is enzymatically inactive. The X-ray structure of a His to Asn mutant of duck delta II crystallin (H162N) with bound argininosuccinate has been determined to 2.3 A resolution using the molecular replacement technique. The overall fold of the protein is similar to other members of the superfamily to which this protein belongs, with the active site located in a cleft formed by three different monomers in the tetramer. The active site of the H162N mutant structure reveals that the side chain of Glu 296 has a different orientation relative to the homologous residue in the H91N mutant structure [Abu-Abed et al. (1997) Biochemistry 36, 14012-14022]. This shift results in the loss of the hydrogen bond between His 162 and Glu 296 seen in the H91N and turkey delta I crystallin structures; this H-bond is believed to be crucial for the catalytic mechanism of ASL/delta II crystallin. Argininosuccinate was found to be bound to residues in each of the three monomers that form the active site. The fumarate moiety is oriented toward active site residues His 162 and Glu 296 and other residues that are part of two of the three highly conserved regions of amino acid sequence in the superfamily, while the arginine moiety of the substrate is oriented toward residues which belong to either domain 1 or domain 2. The analysis of the structure reveals that significant conformational changes occur on substrate binding. The comparison of this structure with the inactive turkey delta I crystallin reveals that the conformation of domain 1 is crucial for substrate affinity and that the delta I protein is almost certainly inactive because it can no longer bind the substrate.
About this StructureAbout this Structure
1DCN is a Single protein structure of sequence from Anas platyrhynchos with as ligand. Active as Argininosuccinate lyase, with EC number 4.3.2.1 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of an inactive duck delta II crystallin mutant with bound argininosuccinate., Vallee F, Turner MA, Lindley PL, Howell PL, Biochemistry. 1999 Feb 23;38(8):2425-34. PMID:10029536
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