Residue 134 determines the dimer-tetramer assembly of nucleoside diphosphate kinase from moderately halophilic bacteria

Tokunaga, Hiroko*; Ishibashi, Matsujiro*; Arisaka, Fimio*; Arai, Shigeki; Kuroki, Ryota; Arakawa, Tsutomu*; Tokunaga, Masao*

nucleoside diphosphate kinase (HaNDK) forms a dimeric assembly and NDK (PaNDK) forms a tetrameric assembly. The mutation of Glu134 to Ala in HaNDK resulted in conversion of the native dimeric structure to the tetramer assembly. Conversely, the mutation of Ala134 to Glu in PaNDK leads to conversion from tetramer to dimer assembly, indicating that a single amino acid substitution at position 134 results in an alteration of the oligomeric structure of NDK. Modeling structure of HaNDK and PaNDK, based on the crystal structure of NDK, suggested sufficient repulsion by Glu134 to disrupt dimer-dimer interaction to form tetramer.