Chemical shift assignments of domain 4 from the phosphohexomutase from Pseudomonas aeruginosa suggest that freeing perturbs its coevolved domain interface

Abstract

A domain needed for the catalytic efficiency of an enzyme model of simple processivity and domain–domain interactions has been characterized by NMR. This domain 4 from phosphomannomutase/phosphoglucomutase (PMM/PGM) closes upon glucose phosphate and mannose phosphate ligands in the active site, and can modestly reconstitute activity of enzyme truncated to domains 1–3. This enzyme supports biosynthesis of the saccharide-derived virulence factors (rhamnolipids, lipo-polysaccharides, and alginate) of the opportunistic bacterial pathogen Pseudomonas aeruginosa. 1H, 13C, and 15N NMR chemical shift assignments of domain 4 of PMM/PGM suggest preservation and independence of its structure when separated from domains 1–3. The face of domain 4 that packs with domain 3 is perturbed in NMR spectra without disrupting this fold. The perturbed residues overlap both the most highly coevolved positions in the interface and residues lining a cavity at the domain interface.

Promotion of Enzyme Flexibility by Dephosphorylation and Coupling to the Catalytic Mechanism of a Phosphohexomutase

“…4A, red and orange spheres). As the isolated D4 fragment of PMM/PGM is notably well folded in solution (28,29), this seems most consistent with a decrease in its conformational mobility in the phosphorylated, ligandbound samples.…”

Induced Structural Disorder as a Molecular Mechanism for Enzyme Dysfunction in Phosphoglucomutase 1 Deficiency

“…Also, as established in other systems [27], the multi-domain architecture of the enzyme could offer advantages, allowing individual domains “fold up” around the site(s) of structural disruption, despite their internal locations in the polypeptide chain. For several related proteins ([28,29] and PDB code: 1WJW), isolated versions of D4 fold correctly, supporting the notion of independent domain folding in this enzyme superfamily.…”

Biology, Mechanism, and Structure of Enzymes in the α- d -Phosphohexomutase Superfamily

“…Typically, the β-sheet in D4 is composed of four or more strands, although for proteins in the PNGM sub-group only three strands are found (Mehra-Chaudhary, Mick, & Beamer, 2011). In several members of the superfamily, it has been shown that D4 is an independently folded unit, maintaining a well-ordered structure in the absence of the other three domains (Schramm et al, 2010; Wei et al, 2014) (see also pdb: 1WJW). This appears to be consistent with the conformational variability of this domain relative to the others that has been noted in multiple proteins in the superfamily (Luebbering et al, 2012).…”