Leopoldseder, Sonja and Hettwer, Stefan and Sterner, Reinhard (2006) Evolution of multi-enzyme complexes: The case of tryptophan synthase. BIOCHEMISTRY, 45 (47). pp. 14111-14119. ISSN 0006-2960,
Full text not available from this repository. (Request a copy)Abstract
The prototypical tryptophan synthase is a stable heterotetrameric alpha-beta beta-alpha complex. The constituting TrpA and TrpB1 subunits, which are encoded by neighboring genes in the trp operon, activate each other in a bi-directional manner. Recently, a novel class of TrpB2 proteins has been identified, whose members contain additional amino acids that might sterically prevent complex formation with TrpA. To test this hypothesis, we characterized the TrpA and TrpB proteins from Sulfolobus solfataricus. This hyperthermophilic archaeon does not contain a TrpB1 protein but instead contains two TrpB2 homologues that are encoded within (TrpB2i) and outside (TrpB2o) the trp operon. We find that TrpB2i and TrpA form a weak and transient complex during catalysis, with a uni-directional activation of TrpA by TrpB2i. In contrast, TrpB2o and TrpA do not form a detectable complex. These results suggest a model for the evolution of the tryptophan synthase in which TrpB2o, TrpB2i, and TrpB1 reflect the stepwise increase of TrpB affinity for TrpA and the refinement of functional subunit interaction, concomitant with the co-localization of the encoding genes in the trp operon.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | STEADY-STATE KINETICS; ESCHERICHIA-COLI; CRYSTAL-STRUCTURE; BIENZYME COMPLEX; SALMONELLA-TYPHIMURIUM; ANTHRANILATE SYNTHASE; ALPHA(2)BETA(2) COMPLEX; GENOME SEQUENCE; ALPHA-SUBUNIT; BETA-SUBUNIT; |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Reinhard Sterner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 18 Jan 2021 09:04 |
| Last Modified: | 18 Jan 2021 09:04 |
| URI: | https://pred.uni-regensburg.de/id/eprint/33745 |
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