Zα Domain From Carassius Auratus PKR-like (PKZ) Converts B-conformation Oligo DNA Contained D (GC) Repeate To Z-conformation

PKZ was the most recently discovered member of eIF2a kinase family in fish. CaPKZ, possessed a conserved eIF2a kinase catalytic domain in C-terminal and two Z-DNA binding domains (Za) in N-terminal. The two Za subdomains were termed Zα1 and Zα2, respectively. The Zα1Zα2 domain act as a regulation domain, and its functions were not so lucid.To investigate the function of PKZ Za and the length and the preference that it can bind to and flip to Z-DNA, we synthesis some Oligo DNA, at the same time, the twelve peptides were expressed in E.coli. The interaction between Za peptide and Oligo DNA has been investigated with CD spectrum. We find First, Too shrot of the length of the Hairpins to form the Z-DNA structure. Second, the shortest Hairpins that can interact with Zα1Zα2 is Hairpin4, while Hairpin3 interact with Zα1Zα1 dramaticly. Third, there are interactions between Zα1Zα2 Oligo DNA that contain GC segment, but no interactions between Zα1Zα2 and Oligo DNA with TA segment and Primer DNA. Fourth, Hairpin6 can be flip to Z-DNA by Zα1Zα1, while Za2Za2 can not.We investigated the nine important amino acid sites which may interact with the DNA backbone and (or) maintain the tertiary structure by titration Hairpin6 with the alanine mutations and substitute mutations peptides. We find, First, N38A, Y42A, P57A and P58A almost lost the whole capability of overturn. The result indicated that N38, Y42, P57 and P58 are very important for ZalZa2 functions. Second, S35A and K56A retain part overturn capability, this result indicate that those two sites are not so important to ZalZa2 functions. Third, we find that the CD titration spectrum of Hairpin6 with the increasing K34A, R39A, W60A peptides were different from with the Wild Type ZalZa2. The intresting results suggest that W60A may converts Hairpin6 DNA in a complete different way in contrast with the results of wild type Zα1Zα2. To understand the different phenomena, W60A needs more continuous investigate.