1tti
From Proteopedia
(New page: 200px<br /><applet load="1tti" size="450" color="white" frame="true" align="right" spinBox="true" caption="1tti, resolution 2.4Å" /> '''THREE NEW CRYSTAL STR...) |
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| - | [[Image:1tti.gif|left|200px]]<br /><applet load="1tti" size=" | + | [[Image:1tti.gif|left|200px]]<br /><applet load="1tti" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1tti, resolution 2.4Å" /> | caption="1tti, resolution 2.4Å" /> | ||
'''THREE NEW CRYSTAL STRUCTURES OF POINT MUTATION VARIANTS OF MONOTIM: CONFORMATIONAL FLEXIBILITY OF LOOP-1,LOOP-4 AND LOOP-8'''<br /> | '''THREE NEW CRYSTAL STRUCTURES OF POINT MUTATION VARIANTS OF MONOTIM: CONFORMATIONAL FLEXIBILITY OF LOOP-1,LOOP-4 AND LOOP-8'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Wild-type triosephosphate isomerase (TIM) is a very stable | + | BACKGROUND: Wild-type triosephosphate isomerase (TIM) is a very stable dimeric enzyme. This dimer can be converted into a stable monomeric protein (monoTIM) by replacing the 15-residue interface loop (loop-3) by a shorter, 8-residue, loop. The crystal structure of monoTIM shows that two active-site loops (loop-1 and loop-4), which are at the dimer interface in wild-type TIM, have acquired rather different structural properties. Nevertheless, monoTIM has residual catalytic activity. RESULTS: Three new structures of variants of monoTIM are presented, a double-point mutant crystallized in the presence and absence of bound inhibitor, and a single-point mutant in the presence of a different inhibitor. These new structures show large structural variability for the active-site loops, loop-1, loop-4 and loop-8. In the structures with inhibitor bound, the catalytic lysine (Lys13 in loop-1) and the catalytic histidine (His95 in loop-4) adopt conformations similar to those observed in wild-type TIM, but very different from the monoTIM structure. CONCLUSIONS: The residual catalytic activity of monoTIM can now be rationalized. In the presence of substrate analogues the active-site loops, loop-1, loop-4 and loop-8, as well as the catalytic residues, adopt conformations similar to those seen in the wild-type protein. These loops lack conformational flexibility in wild-type TIM. The data suggest that the rigidity of these loops in wild-type TIM, resulting from subunit-subunit contacts at the dimer interface, is important for optimal catalysis. |
==About this Structure== | ==About this Structure== | ||
| - | 1TTI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Trypanosoma_brucei_brucei Trypanosoma brucei brucei] with PGA as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Triose-phosphate_isomerase Triose-phosphate isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.1 5.3.1.1] Full crystallographic information is available from [http:// | + | 1TTI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Trypanosoma_brucei_brucei Trypanosoma brucei brucei] with <scene name='pdbligand=PGA:'>PGA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Triose-phosphate_isomerase Triose-phosphate isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.1 5.3.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TTI OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Triose-phosphate isomerase]] | [[Category: Triose-phosphate isomerase]] | ||
[[Category: Trypanosoma brucei brucei]] | [[Category: Trypanosoma brucei brucei]] | ||
| - | [[Category: Kishan, K | + | [[Category: Kishan, K V.Radha.]] |
| - | [[Category: Wierenga, R | + | [[Category: Wierenga, R K.]] |
[[Category: PGA]] | [[Category: PGA]] | ||
[[Category: isomerase(intramolecular oxidoreductase)]] | [[Category: isomerase(intramolecular oxidoreductase)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:17:11 2008'' |
Revision as of 13:17, 21 February 2008
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THREE NEW CRYSTAL STRUCTURES OF POINT MUTATION VARIANTS OF MONOTIM: CONFORMATIONAL FLEXIBILITY OF LOOP-1,LOOP-4 AND LOOP-8
Overview
BACKGROUND: Wild-type triosephosphate isomerase (TIM) is a very stable dimeric enzyme. This dimer can be converted into a stable monomeric protein (monoTIM) by replacing the 15-residue interface loop (loop-3) by a shorter, 8-residue, loop. The crystal structure of monoTIM shows that two active-site loops (loop-1 and loop-4), which are at the dimer interface in wild-type TIM, have acquired rather different structural properties. Nevertheless, monoTIM has residual catalytic activity. RESULTS: Three new structures of variants of monoTIM are presented, a double-point mutant crystallized in the presence and absence of bound inhibitor, and a single-point mutant in the presence of a different inhibitor. These new structures show large structural variability for the active-site loops, loop-1, loop-4 and loop-8. In the structures with inhibitor bound, the catalytic lysine (Lys13 in loop-1) and the catalytic histidine (His95 in loop-4) adopt conformations similar to those observed in wild-type TIM, but very different from the monoTIM structure. CONCLUSIONS: The residual catalytic activity of monoTIM can now be rationalized. In the presence of substrate analogues the active-site loops, loop-1, loop-4 and loop-8, as well as the catalytic residues, adopt conformations similar to those seen in the wild-type protein. These loops lack conformational flexibility in wild-type TIM. The data suggest that the rigidity of these loops in wild-type TIM, resulting from subunit-subunit contacts at the dimer interface, is important for optimal catalysis.
About this Structure
1TTI is a Single protein structure of sequence from Trypanosoma brucei brucei with as ligand. Active as Triose-phosphate isomerase, with EC number 5.3.1.1 Full crystallographic information is available from OCA.
Reference
Three new crystal structures of point mutation variants of monoTIM: conformational flexibility of loop-1, loop-4 and loop-8., Borchert TV, Kishan KV, Zeelen JP, Schliebs W, Thanki N, Abagyan R, Jaenicke R, Wierenga RK, Structure. 1995 Jul 15;3(7):669-79. PMID:8591044
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