BORCHERT, TV and KISHAN, KVR and ZEELEN, JP and SCHLIEBS, W and THANKI, N and ABAGYAN, R and JAENICKE, R and WIERENGA, RK (1995) 3 NEW CRYSTAL-STRUCTURES OF POINT MUTATION VARIANTS OF MONOTIM - CONFORMATIONAL FLEXIBILITY OF LOOP-1, LOOP-4 AND LOOP-8. STRUCTURE, 3 (7). pp. 669-679. ISSN 0969-2126, 1878-4186
Full text not available from this repository.Abstract
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 wildtype TIM, resulting from subunit-subunit contacts at the dimer interface, is important for optimal catalysis.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TRYPANOSOMAL TRIOSEPHOSPHATE ISOMERASE; ESCHERICHIA-COLI; RESOLUTION; CATALYSIS; PROTEIN; COMPLEX; CHICKEN; ERRORS; YEAST; MAPS; ASSEMBLY; FLEXIBILITY; LOOPS; SUBUNIT; TRIOSEPHOSPHATE ISOMERASE (TIM) |
| Depositing User: | Dr. Gernot Deinzer |
| Last Modified: | 19 Oct 2022 08:37 |
| URI: | https://pred.uni-regensburg.de/id/eprint/52431 |
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