Tryptophan synthase: the workings of a channeling nanomachine |
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Authors: | Dunn Michael F Niks Dimitri Ngo Huu Barends Thomas R M Schlichting Ilme |
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Affiliation: | Department of Biochemistry, University of California, Riverside, CA 92521, USA. |
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Abstract: | Substrate channeling between enzymes has an important role in cellular metabolism by compartmentalizing cytoplasmic synthetic processes. The bacterial tryptophan synthases are multienzyme nanomachines that catalyze the last two steps in L-tryptophan biosynthesis. The common metabolite indole is transferred from one enzyme to the other in each alphabeta-dimeric unit of the alpha2beta2 complex via an interconnecting 25-A-long tunnel. Recent solution studies of the Salmonella typhimurium alpha2beta2 complex coupled with X-ray crystal-structure determinations of complexes with substrates, intermediates and substrate analogs have driven important breakthroughs concerning the identification of the linkages between the bi-enzyme complex structure, catalysis at the alpha- and beta-active sites, and the allosteric regulation of substrate channeling. |
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