tailieunhanh - Báo cáo khoa học: Crystal structures of Drosophila mutant translin and characterization of translin variants reveal the structural plasticity of translin proteins

Translin protein is highly conserved in eukaryotes. Human translin binds both ssDNA and RNA. Its nucleic acid binding site results from a combina-tion of basic regions in the octameric structure. We report here the first bio-chemical characterization of wild-typeDrosophila melanogaster(drosophila) translin and a chimeric translin, and present A ˚ resolution crystal struc-tures of drosophila P168S mutant translin from two crystal forms. | ỊFEBS Journal Crystal structures of Drosophila mutant translin and characterization of translin variants reveal the structural plasticity of translin proteins Gagan D. Gupta1 Ravindra D. Makde1 Basuthkar J. Rao2 and Vinay Kumar1 1 High Pressure Physics Division Bhabha Atomic Research Centre Mumbai India 2 Department of BiologicalSciences Tata Institute of FundamentalResearch Mumbai India Keywords chimeric translin crystal structure Drosophila melanogaster translin oligomerization P168S mutant Correspondence V. Kumar High Pressure Physics Division Bhabha Atomic Research Centre Mumbai 400 085 India Fax 91 22 25505151 Tel 91 22 25593761 E-mail vinay@ Received 8 May 2008 revised 23 June 2008 accepted 24 June 2008 doi Translin protein is highly conserved in eukaryotes. Human translin binds both ssDNA and RNA. Its nucleic acid binding site results from a combination of basic regions in the octameric structure. We report here the first biochemical characterization of wild-type Drosophila melanogaster drosophila translin and a chimeric translin and present A resolution crystal structures of drosophila P168S mutant translin from two crystal forms. The wild-type drosophila translin most likely exists as an octamer decamer and binds to the ssDNA Bcl-CL1 sequence. In contrast ssDNA binding-incompetent drosophila P168S mutant translin exists as a tetramer. The structures of the mutant translin are identical in both crystal forms and their C-termi-nal residues are disordered. The chimeric protein possessing two nucleic acid binding motifs of drosophila translin the C-terminal residues of human translin and serine at position 168 attains the octameric state and binds to ssDNA. The present studies suggest that the oligomeric status of translin critically influences the DNA binding properties of translin proteins. Human translin a 27-kDa protein binds to ssDNA and RNA. It recognizes chromosomal breakpoint sequences at ssDNA ends with