2CLM

Tryptophan Synthase (external aldimine state) in complex with N-(4'- trifluoromethoxybenzoyl)-2-amino-1-ethylphosphate (F6F)

Summary for 2CLM

• Entry DOI: 10.2210/pdb2clm/pdb
• Related: 1A50 1A5A 1A5B 1A5S 1BEU 1BKS 1C29 1C8V 1C9D 1CW2 1CX9 1FUY 1K3U 1K7E 1K7F 1K7X 1K8X 1K8Y 1K8Z 1KFB 1KFC 1KFE 1KFJ 1KFK 1QOP 1QOQ 1TJP 1TTP 1TTQ 1UBS 1WBJ 2CLE 2CLF 2CLI 2CLK 2CLL 2CLO 2TRS 2TSY 2TYS 2WSY
• Descriptor: TRYPTOPHAN SYNTHASE ALPHA CHAIN, TRYPTOPHAN SYNTHASE BETA CHAIN, 2-{[4-(TRIFLUOROMETHOXY)BENZOYL]AMINO}ETHYL DIHYDROGEN PHOSPHATE, ... (6 entities in total)
• Functional Keywords: aromatic amino acid biosynthesis, carbon-oxygen lyase, amino-acid biosynthesis, tryptophan biosynthesis, lyase, allosteric enzyme, pyridoxal phosphate
• Biological source: SALMONELLA TYPHIMURIUM; More
• Total number of polymer chains: 2
• Total formula weight: 72244.99

Authors

Ngo, H.,Kimmich, N.,Harris, R.,Niks, D.,Blumenstein, L.,Kulik, V.,Barends, T.R.,Schlichting, I.,Dunn, M.F. (deposition date: 2006-04-28, release date: 2007-06-12, Last modification date: 2024-05-08)

Primary citation

Ngo, H.,Kimmich, N.,Harris, R.,Niks, D.,Blumenstein, L.,Kulik, V.,Barends, T.R.,Schlichting, I.,Dunn, M.F.
Allosteric Regulation of Substrate Channeling in Tryptophan Synthase: Modulation of the L-Serine Reaction in Stage I of the Beta-Reaction by Alpha-Site Ligands.
Biochemistry, 46:7740-, 2007

PubMed Abstract: In the tryptophan synthase bienzyme complex, indole produced by substrate cleavage at the alpha-site is channeled to the beta-site via a 25 A long tunnel. Within the beta-site, indole and l-Ser react with pyridoxal 5'-phosphate in a two-stage reaction to give l-Trp. In stage I, l-Ser forms an external aldimine, E(Aex1), which converts to the alpha-aminoacrylate aldimine, E(A-A). Formation of E(A-A) at the beta-site activates the alpha-site >30-fold. In stage II, indole reacts with E(A-A) to give l-Trp. The binding of alpha-site ligands (ASLs) exerts strong allosteric effects on the reaction of substrates at the beta-site: the distribution of intermediates formed in stage I is shifted in favor of E(A-A), and the binding of ASLs triggers a conformational change in the beta-site to a state with an increased affinity for l-Ser. Here, we compare the behavior of new ASLs as allosteric effectors of stage I with the behavior of the natural product, d-glyceraldehyde 3-phosphate. Rapid kinetics and kinetic isotope effects show these ASLs bind with affinities ranging from micro- to millimolar, and the rate-determining step for conversion of E(Aex1) to E(A-A) is increased by 8-10-fold. To derive a structure-based mechanism for stage I, X-ray structures of both the E(Aex1) and E(A-A) states complexed with the different ASLs were determined and compared with structures of the ASL complexes with the internal aldimine [Ngo, H., Harris, R., Kimmich, N., Casino, P., Niks, D., Blumenstein, L., Barends, T. R., Kulik, V., Weyand, M., Schlichting, I., and Dunn, M. F. (2007) Biochemistry 46, 7713-7727].

PubMed: 17559232
DOI: 10.1021/BI7003872

Experimental method

X-RAY DIFFRACTION (1.51 Å)