PDBsum entry 5ypp

Transferase

PDB id: 5ypp

Contents

Protein chains

(+ 0 more) 90 a.a.

Ligands

VAL ×6

PEG ×9

ACT

Waters ×134

PDB id:

5ypp

Name:

Transferase

Title:

Crystal structure of ilvn.Val-1a

Structure:

Acetolactate synthase isozyme 1 small subunit. Chain: a, b, c, d, e, f. Synonym: acetohydroxy-acid synthase i small subunit,als-i. Engineered: yes

Source:

Escherichia coli (strain k12). Organism_taxid: 83333. Strain: k12. Gene: ilvn, b3670, jw3645. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.90Å R-factor: 0.150 R-free: 0.170

Authors:

S.P.Sarma,A.Bansal,H.Schindelin,B.Demeler

Key ref:

A.Bansal et al. (2019). Crystallographic Structures of IlvN·Val/Ile Complexes: Conformational Selectivity for Feedback Inhibition of Aceto Hydroxy Acid Synthases. Biochemistry, 58, 1992-2008. PubMed id: 30887800 DOI: 10.1021/acs.biochem.9b00050

Date:

02-Nov-17 Release date: 19-Sep-18

Protein chains

P0ADF8  (ILVN_ECOLI) -  Acetolactate synthase isozyme 1 small subunit from Escherichia coli (strain K12)

Seq: 96 a.a.

Struc: 90 a.a.

Enzyme reactions

• Enzyme class: E.C.2.2.1.6 - acetolactate synthase.
• Pathway: Isoleucine and Valine Biosynthesis
• Reaction: 2 pyruvate + H⁺ = (2S)-2-acetolactate + CO2

2 × pyruvate + H(+) (Bound ligand (Het Group name = VAL) matches with 55.56% similarity) = (2S)-2-acetolactate + CO2 (Bound ligand (Het Group name = ACT) matches with 75.00% similarity)

• Cofactor: Thiamine diphosphate

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1021/acs.biochem.9b00050

Biochemistry 58:1992-2008 (2019)

PubMed id: 30887800

Crystallographic Structures of IlvN·Val/Ile Complexes: Conformational Selectivity for Feedback Inhibition of Aceto Hydroxy Acid Synthases.

A.Bansal, N.M.Karanth, B.Demeler, H.Schindelin, S.P.Sarma.

ABSTRACT

Conformational factors that predicate selectivity for valine or isoleucine binding to IlvN leading to the regulation of aceto hydroxy acid synthase I (AHAS I) of Escherichia coli have been determined for the first time from high-resolution (1.9-2.43 Å) crystal structures of IlvN·Val and IlvN·Ile complexes. The valine and isoleucine ligand binding pockets are located at the dimer interface. In the IlvN·Ile complex, among residues in the binding pocket, the side chain of Cys⁴³ is 2-fold disordered (χ₁ angles of gauche^- and trans). Only one conformation can be observed for the identical residue in the IlvN·Val complexes. In a reversal, the side chain of His⁵³, located at the surface of the protein, exhibits two conformations in the IlvN·Val complex. The concerted conformational switch in the side chains of Cys⁴³ and His⁵³ may play an important role in the regulation of the AHAS I holoenzyme activity. A significant result is the establishment of the subunit composition in the AHAS I holoenzyme by analytical ultracentrifugation. Solution nuclear magnetic resonance and analytical ultracentrifugation experiments have also provided important insights into the hydrodynamic properties of IlvN in the ligand-free and -bound states. The structural and biophysical data unequivocally establish the molecular basis for differential binding of the ligands to IlvN and a rationale for the resistance of IlvM to feedback inhibition by the branched-chain amino acids.