User:Amer Ali/Sandbox 1
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| - | == | + | == Tryptophan Synthase == |
| - | <StructureSection load=' | + | <StructureSection load='1wbj' size='340' side='right' caption='Tryptophan synthase structure with alpha subunit (outer turqoise and light blue) and beta subunit (middle green and light green). Pyridoxal-phosphate, glycerol-3-phosphate, and Na+ ion shown within the structure (purple spheres) ' scene=''> |
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| - | + | == Introduction == | |
| + | Tryptophan synthase (TrpS) is an enzyme mainly found in bacteria, plants, and fungi <ref name= "Kulik"> DOI: 10.1016/j.jmb.2005.07.014 </ref>. TrpS must be functional for pathogenic bacteria in macrophages to survive, and it is used as a way to avoid host immune response. Tryptophan is necessary for bacteria and lower eukaryotic organisms for protein synthesis. Salmonella typhimurium and Escherichia coli serve as model organisms for the understanding of TrpS processes and structure <ref name= "Kulik"> DOI: 10.1016/j.jmb.2005.07.014 </ref>. | ||
== Function == | == Function == | ||
| + | TrpS is a pyridoxal 5’-phosphate (PLP)-dependent enzyme. TrpS has an alpha and beta chain that form a linear alpha-beta-beta-alpha heterotetrameric complex <ref name= "Michalska"> PMID: 31316809 </ref>. This is termed as the alpha2beta2 complex, and each subunit is also referred to as TrpA and TrpB for the alpha and beta subunits respectively. The alpha active site contains catalytic residues Glu and Asp, and a hydrophobic intramolecular tunnel allows for the transport of indole from the alpha subunit active site to the beta subunit active site (Miles 2001). The alpha and beta chain are encoded by trpA and trpB genes that are involved in TrpS regulatory operon. In bacteria and plants, the alpha and beta chains are separate, but in fungi the two chains are fused into one protein (Tryptophan synthase, alpha chain, active site). The alpha2beta2 tetramer complex contains pyridoxal-phosphate, glycerol-3-phosphate, Na+ ions. Another key site in tryptophan synthase is the monovalent cation (MVC) site, which is made up of cations like Na+ and K+, along with Cs+ <ref name= "Dierkers"> DOI: 10.1021/bi9008374</ref> <ref name= "Dunn"> DOI: 10.1007/978-1-4614-1533-6244 </ref> (Dunn, 2013). For regulation, TrpA and TrpB cycle between low-activity open conformation and a high-activity closed state. This is done by the bining of an IGP substrate to TrpA which promotes the high activity closed state which activates the TrpB high activity closed state. The states are reset back to low activity open conformation by the production of L-Trp external aldimine <ref name= "Michalska"> PMID: 31316809 </ref>. | ||
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== Disease == | == Disease == | ||
Revision as of 02:01, 30 April 2022
Tryptophan Synthase
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References
- ↑ 1.0 1.1 Kulik V, Hartmann E, Weyand M, Frey M, Gierl A, Niks D, Dunn MF, Schlichting I. On the structural basis of the catalytic mechanism and the regulation of the alpha subunit of tryptophan synthase from Salmonella typhimurium and BX1 from maize, two evolutionarily related enzymes. J Mol Biol. 2005 Sep 23;352(3):608-20. PMID:16120446 doi:10.1016/j.jmb.2005.07.014
- ↑ 2.0 2.1 Michalska K, Gale J, Joachimiak G, Chang C, Hatzos-Skintges C, Nocek B, Johnston SE, Bigelow L, Bajrami B, Jedrzejczak RP, Wellington S, Hung DT, Nag PP, Fisher SL, Endres M, Joachimiak A. Conservation of the structure and function of bacterial tryptophan synthases. IUCrJ. 2019 May 29;6(Pt 4):649-664. doi: 10.1107/S2052252519005955. eCollection, 2019 Jul 1. PMID:31316809 doi:http://dx.doi.org/10.1107/S2052252519005955
- ↑ Dierkers AT, Niks D, Schlichting I, Dunn MF. Tryptophan synthase: structure and function of the monovalent cation site. Biochemistry. 2009 Nov 24;48(46):10997-1010. doi: 10.1021/bi9008374. PMID:19848417 doi:http://dx.doi.org/10.1021/bi9008374
- ↑ doi: https://dx.doi.org/10.1007/978-1-4614-1533-6244
