A PDZ-like domain mediates the dimerization of 11R-lipoxygenase.

Lipoxygenases (LOXs), participating in inflammatory processes and cancer, are a family of enzymes with high potential as drug targets. Various allosteric effects have been observed with different LOX isozymes (e.g. lipid/ATP binding, phosphorylation), yet there is a lot of uncertainty concerning the regulation of these enzymes. It has been recently found that a number of LOXs form dimers, extending the list of possible allosteric mechanisms with oligomerization. Coral 11R-LOX is, unlike several mammalian counterparts, a stable dimer in solution facilitating quaternary structure studies that demand high sample homogeneity. By combining previous crystallographic data of 11R-LOX with small-angle X-ray scattering and chemical cross-linking, we were able to narrow down the possible dimerization interfaces, and subsequently determined the correct assembly by site-directed mutagenesis of potential contacting residues. The region of interest is located in the vicinity of an α+β formation in the catalytic domain, also coined the PDZ-like domain. Being situated just between the active site and the dimer interface, our results further implicate this putative subdomain in the regulation of LOXs.