Research in the Berry lab is focused on selenoproteins, proteins containing the essential trace element, selenium, in the form of an unusual amino acid, selenocysteine. Most selenoproteins in higher organisms function either as antioxidants or in maintaining cellular redox balance. These functions explain the long-known antioxidant properties of selenium. In all selenoproteins whose functions are known, selenocysteine serves as the catalytic center of an enzyme, and its presence is required for optimal enzyme function.
Selenocysteine, designated the 21st amino acid, is specified in the genetic code by UGA codons, which typically serve as stop codons. The process of inserting selenocysteine into proteins is unique to this amino acid, and occurs in organisms ranging from bacteria to man. Cotranslational incorporation of selenocysteine requires a specialized tRNA with an anticodon complementary to UGA, a specialized elongation factor that recognizes this tRNA, and specific secondary structures in selenoprotein mRNAs. These stem-loop secondary structures either recruit the elongation factor directly (in prokaryotes), or recruit another protein, which in turn recruits the elongation factor (in eukaryotes).
Our research focuses on two major areas, the mechanism and efficiency of selenoprotein biosynthesis, and the functions of selenoproteins in health and disease.