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'''LARGE SCALE STRUCTURAL REARRANGEMENTS OF THE FRONT LOOPS IN MONOMERISED TRIOSEPHOSPHATE ISOMERASE, AS DEDUCED FROM THE COMPARISON OF THE STRUCTURAL PROPERTIES OF MONOTIM AND ITS POINT MUTATION VARIANT MONOSS''' | '''LARGE SCALE STRUCTURAL REARRANGEMENTS OF THE FRONT LOOPS IN MONOMERISED TRIOSEPHOSPHATE ISOMERASE, AS DEDUCED FROM THE COMPARISON OF THE STRUCTURAL PROPERTIES OF MONOTIM AND ITS POINT MUTATION VARIANT MONOSS''' | ||
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[[Category: Kishan, K V.Radha.]] | [[Category: Kishan, K V.Radha.]] | ||
[[Category: Wierenga, R K.]] | [[Category: Wierenga, R K.]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 01:40:45 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 01:40, 3 May 2008
LARGE SCALE STRUCTURAL REARRANGEMENTS OF THE FRONT LOOPS IN MONOMERISED TRIOSEPHOSPHATE ISOMERASE, AS DEDUCED FROM THE COMPARISON OF THE STRUCTURAL PROPERTIES OF MONOTIM AND ITS POINT MUTATION VARIANT MONOSS
OverviewOverview
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 StructureAbout this Structure
1MSS is a Single protein structure of sequence from Trypanosoma brucei brucei. Full crystallographic information is available from OCA.
ReferenceReference
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 Page seeded by OCA on Sat May 3 01:40:45 2008