Tomato multifunctional nuclease TBN1 belongs to the type I nuclease family, which plays an important role in apoptotic processes and cell senescence in plants. The newly solved structure of the N211D mutant is reported. Although the main crystal-packing motif (the formation of superhelices) is conserved, the details differ among the known structures. A phosphate ion was localized in the active site of the enzyme. The binding of the surface loop to the active centre is stabilized by the phosphate ion, which correlates with the observed aggregation of TBN1 in phosphate buffer. The conserved binding of the surface loop to the active centre suggests biological relevance of the contact in a regulatory function or in the formation of oligomers.

• Keywords
• TBN1, superhelix, tomato multifunctional nuclease, type I nuclease,
• MeSH
• Endodeoxyribonucleases chemistry   genetics   metabolism   MeSH
• Phosphates metabolism   MeSH
• Crystallization MeSH
• Molecular Sequence Data MeSH
• Multienzyme Complexes chemistry   genetics   metabolism   MeSH
• Plant Proteins chemistry   genetics   metabolism   MeSH
• Protein Structure, Secondary MeSH
• Amino Acid Sequence MeSH
• Solanum lycopersicum enzymology   genetics   MeSH
• Binding Sites physiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Endodeoxyribonucleases MeSH
• Phosphates MeSH
• Multienzyme Complexes MeSH
• Plant Proteins MeSH
• superhelical DNA endonuclease MeSH Browser

The endonuclease TBN1 from Solanum lycopersicum (tomato) was expressed in Nicotiana benthamiana leaves and purified with suitable quality and in suitable quantities for crystallization experiments. Two crystal forms (orthorhombic and rhombohedral) were obtained and X-ray diffraction experiments were performed. The presence of natively bound Zn2+ ions was confirmed by X-ray fluorescence and by an absorption-edge scan. X-ray diffraction data were collected from the orthorhombic (resolution of 5.2 Å) and rhombohedral (best resolution of 3.2 Å) crystal forms. SAD, MAD and MR methods were applied for solution of the phase problem, with partial success. TBN1 contains three Zn2+ ions in a similar spatial arrangement to that observed in nuclease P1 from Penicillium citrinum.

• MeSH
• Deoxyribonucleases chemistry   genetics   MeSH
• Ions chemistry   MeSH
• Protein Conformation MeSH
• Crystallization MeSH
• Crystallography, X-Ray MeSH
• Molecular Sequence Data MeSH
• Recombinant Proteins chemistry   genetics   MeSH
• Plant Proteins chemistry   genetics   MeSH
• Solanum lycopersicum chemistry   genetics   MeSH
• Zinc chemistry   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Deoxyribonucleases MeSH
• Ions MeSH
• Recombinant Proteins MeSH
• Plant Proteins MeSH
• Zinc MeSH