Structure and function of sulfotransferases

Sulfotransferases (STs) catalyze the transfer reaction of the sulfate group from the ubiquitous donor 3 ' -phosphoadenosine 5 ' -phosphosulfate (PAPS) to an acceptor group of numerous substrates, This reaction, often referred to as sulfuryl transfer, sulfation, or sulfonation, is widely observed fro m bacteria to humans and plays a key role in various biological processes s uch as cell communication, growth and development, and defense, The cytosol ic STs sulfate small molecules such as steroids, bioamines, and therapeutic drugs, while the Golgi-membrane counterparts sulfate large molecules inclu ding glucosaminylglycans and proteins. We have now solved the X-ray crystal structures of four cytosolic and one membrane ST. All five STs are globula r proteins composed of a single alpha/beta domain with the characteristic f ive-stranded beta -sheet, The beta -sheet constitutes the core of the Paps- binding and catalytic sites. Structural analysis of the PAPS-, PAP-, substr ate-, and/or orthovanadate (VO43-)-bound enzymes has also revealed the comm on molecular mechanism of the transfer reaction catalyzed by sulfotransfers es. The X-ray crystal structures have opened a new era for the study of sul fotransferases. (C) 2001 Academic Press.