Structural Determination of the ZZ Domain of Cytoplasmic Polyadenlation Element Binding Protein

Author

Daniel Merkel, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2012

Degree Name

Master of Science

Department

Chemistry

First Advisor

Lee, Brian

Abstract

Cytoplasmic polyadenylation-element binding protein (CPEB) is required for the translational regulation in multiple cell types. CPEB is known to play important roles in early germ cell development, in neuronal synaptic plasticity, and in the process of cellular senescence. CPEB is able to control translation by first interacting with a specific sequence of mRNA known as the CPE site. CPEB recognizes a specific sequence of mRNA, called the cytoplasmic polyadenylation element. This is a uracil rich sequence that is located on the 3' UTR of mRNA. Once CPEB is bound to the CPE site, CPEB can interact with other proteins. CPEB is most notably known for interacting with a cleavage and polyadenylation specificity factor (CPSF), with a poly(A)-specific ribonuclease, and with a poly(A) polymerase in the Gld2 family. This complex of proteins controls polyadenylation on the 3' end of mRNA. By controlling the lengthening of the poly(A) tail, translation can be regulated. CPEB is believed to contain two RNA recognition motifs and a zinc binding region on the N-terminus. The zinc binding region contains six cysteine and two histidine residues that bind to two zinc atoms in a tetrahedral geometry. Using NMR spectroscopy, the structure of zinc binding region of CPEB1 was determined. This protein was shown to bind to two zinc ions in a cross-braced topology. The zinc binding region of CPEB was also determined that the correct classification for this zinc finger is a ZZ domain.