Allostery and the dynamic oligomerization of porphobilinogen synthase.

ABSTRACT: The structural basis for allosteric regulation of porphobilinogen synthase (PBGS) is modulation of a quaternary structure equilibrium between octamer and hexamer (via dimers), which is represented schematically as 8mer ⇔ 2mer ⇔ 2mer∗⇔ 6mer∗. The "∗" represents a reorientation between two domains of each subunit that occurs in the dissociated state because it is sterically forbidden in the larger multimers. Allosteric effectors of PBGS are both intrinsic and extrinsic and are phylogenetically variable. In some species this equilibrium is modulated intrinsically by magnesium which binds at a site specific to the 8mer. In other species this equilibrium is modulated intrinsically by pH with the guanidinium group of an arginine being spatially equivalent to the allosteric magnesium ion. In huma

SUBMITTER: Jaffe EK 

PROVIDER: S-EPMC3291741 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature