An unusually small dimer interface is observed in all available crystal structures of cytosolic sulfotransferases

Abstract

Cytosolic sulfotransferases catalyze the sulfonation of hormones, metabolites, and xeno-biotics. Many of these proteins have been shown to form homodimers and hetero-dimers. An unusually small dimer interface was previously identified by Petrotchenko et al. (FEBS Lett 2001;490:39-43) by cross-linking, protease digestion, and mass spectrome-try and verified by site-directed mutagenesis. Analysis of the crystal packing interfaces in all 28 available crystal structures consisting of 17 crystal forms showsthatthisinterfaceoccurs in all of them. With a small number of exceptions, the publicly available databases of biological assemblies contain either monomers or incorrect dimers. Even crystal structures of mouse SULT1E1, which is a monomer in solution, contain the common dimeric interface, although distorted and missing two important salt bridges. © 2008 wiley-Liss, inc.