title: Remote Control by Inter-Enzyme Allostery: A Novel Paradigm for Regulation of the Shikimate Pathway.
abstract: DAHP synthase and chorismate mutase catalyze key steps in the shikimate biosynthetic pathway en route to aromatic amino acids. In Mycobacterium tuberculosis, chorismate mutase (MtCM; Rv0948c), located at the branch point toward phenylalanine and tyrosine, has poor activity on its own. However, it is efficiently activated by the first enzyme of the pathway, DAHP synthase (MtDS; Rv2178c), through formation of a non-covalent MtCM-MtDS complex. Here, we show how MtDS serves as an allosteric platform for feedback regulation of both enzymes, using X-ray crystallography, small-angle X-ray scattering, size-exclusion chromatography, and multi-angle light scattering. Crystal structures of the fully inhibited MtDS and the allosterically down-regulated MtCM-MtDS complex, solved at 2.8 and 2.7Å, respectively, reveal how effector binding at the internal MtDS subunit interfaces regulates the activity of MtDS and MtCM. While binding of all three metabolic end products to MtDS shuts down the entire pathway, the binding of phenylalanine jointly with tyrosine releases MtCM from the MtCM-MtDS complex, hence suppressing MtCM activation by 'inter-enzyme allostery'. This elegant regulatory principle, invoking a transient allosteric enzyme interaction, seems to be driven by dynamics and is likely a general strategy used by nature.
authors.affiliation: Department of Chemistry, University of Oslo, NO-0315 Oslo, Norway.
authors.forename: Steffi
authors.initials: S
authors.lastname: Munack
authors.affiliation: Laboratory of Organic Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Roderer
authors.affiliation: Department of Chemistry, University of Oslo, NO-0315 Oslo, Norway; European Synchrotron Radiation Facility, FR-38027 Grenoble, France.
authors.forename: Mats
authors.initials: M
authors.lastname: Ökvist
authors.affiliation: Laboratory of Organic Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Jurate
authors.initials: J
authors.lastname: Kamarauskaite
authors.affiliation: Laboratory of Organic Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Severin
authors.initials: S
authors.lastname: Sasso
authors.affiliation: Department of Chemistry, University of Oslo, NO-0315 Oslo, Norway.
authors.forename: André
authors.initials: A
authors.lastname: van Eerde
authors.affiliation: Laboratory of Organic Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland. Electronic address: kast@org.chem.ethz.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Kast
authors.affiliation: Department of Chemistry, University of Oslo, NO-0315 Oslo, Norway. Electronic address: ute.krengel@kjemi.uio.no.
authors.forename: Ute
authors.initials: U
authors.lastname: Krengel
mesh_terms: D010723:3-Deoxy-7-Phosphoheptulonate Synthase / Q000737:chemistry* / Q000378:metabolism*; D000494:Allosteric Regulation; D002826:Chorismate Mutase / Q000737:chemistry* / Q000378:metabolism*; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D000067493:Dynamic Light Scattering; D053858:Metabolic Networks and Pathways; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D011485:Protein Binding; D053838:Scattering, Small Angle; D012765:Shikimic Acid / Q000378:metabolism*
chemical_list: D012765:Shikimic Acid; D010723:3-Deoxy-7-Phosphoheptulonate Synthase; D002826:Chorismate Mutase
keywords: Mycobacterium tuberculosis Rv2178c and Rv0948c; X-ray crystal structure; enzyme catalysis; metabolic pathway; multi-enzyme complex