After the recent publication in the Journal of Biophysical Chemistry entitled “Retracted HIV Study Provides New Information about the Status of the in Vitro Inhibition of DNA Replication by Back-bone Methylation”, i...After the recent publication in the Journal of Biophysical Chemistry entitled “Retracted HIV Study Provides New Information about the Status of the in Vitro Inhibition of DNA Replication by Back-bone Methylation”, it is of importance to review the results of Buck’s group on the synthesis and conformation analyses of phosphate-methylated RNAs in order to afford information on the absence of a further investigation with regard to this de facto acceptable approach. In fact these compounds belong to the very first group of RNAs with a modified neutral backbone by phosphatemethylation. In contrast to the corresponding phosphate-methylated DNAs with a frozen B-conformation, the phosphate-methylated RNAs show an A-conformation. The latter is a prerequisite for duplex formation with (complementary) (natural) RNA. A number of experiments support this fundamental statement. After the HIV study was retracted, the overall results concerning the phosphate-methylated RNAs were published without mentioning Buck’s initial proof of concept and his contributions. Generally, the (modified) dimer RNAs and DNAs possess a number of specific biophysical properties. A novel explanation is given for conflicting structural determinations.展开更多
The crystal structure of the title compound （C34H47NTO9, Mr = 697.79） has been determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21 with a = 9.000（8）, b = 11.360（10）...The crystal structure of the title compound （C34H47NTO9, Mr = 697.79） has been determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21 with a = 9.000（8）, b = 11.360（10）, c = 17.841（15.）/k, β = 97.083（14）°, V = 1810（3）A^3, Z = 2, F（000） = 744, D,.= 1.280 g/cm^3,/t = 0.094 mm^-1, the final R = 0.0721 and wR = 0.1942 for 2479 observed reflections with I 〉 2σ（I）. The two methyl groups attached to the cyclobutane ring are cis oriented. An intramolecular hydrogen bond （N（6）-H（6）…O（8）） introduces rigidity into the title molecule and the crystal structure is stabilized by intermolecular N-H…O hydrogen bonds.展开更多
The human Gadd45 protein family plays critical roles in DNA repair,negative growth control,genomic stability,cell cycle checkpoints and apoptosis.Here we report the crystal structure of human Gadd45,revealing a unique...The human Gadd45 protein family plays critical roles in DNA repair,negative growth control,genomic stability,cell cycle checkpoints and apoptosis.Here we report the crystal structure of human Gadd45,revealing a unique dimer formed via a bundle of four parallel helices,involving the most conserved residues among the Gadd45 isoforms.Mutational analysis of human Gadd45 identified a conserved,highly acidic patch in the central region of the dimer for interaction with the proliferating cell nuclear antigen(PCNA),p21 and cdc2,suggesting that the parallel dimer is the active form for the interaction.Cellular assays indicate that:(1)dimerization of Gadd45 is necessary for apoptosis as well as growth inhibition,and that cell growth inhibition is caused by both cell cycle arrest and apoptosis;(2)a conserved and highly acidic patch on the dimer surface,including the important residues Glu87 and Asp89,is a putative interface for binding proteins related to the cell cycle,DNA repair and apoptosis.These results reveal the mechanism of self-association by Gadd45 proteins and the importance of this self-association for their biological function.展开更多
文摘After the recent publication in the Journal of Biophysical Chemistry entitled “Retracted HIV Study Provides New Information about the Status of the in Vitro Inhibition of DNA Replication by Back-bone Methylation”, it is of importance to review the results of Buck’s group on the synthesis and conformation analyses of phosphate-methylated RNAs in order to afford information on the absence of a further investigation with regard to this de facto acceptable approach. In fact these compounds belong to the very first group of RNAs with a modified neutral backbone by phosphatemethylation. In contrast to the corresponding phosphate-methylated DNAs with a frozen B-conformation, the phosphate-methylated RNAs show an A-conformation. The latter is a prerequisite for duplex formation with (complementary) (natural) RNA. A number of experiments support this fundamental statement. After the HIV study was retracted, the overall results concerning the phosphate-methylated RNAs were published without mentioning Buck’s initial proof of concept and his contributions. Generally, the (modified) dimer RNAs and DNAs possess a number of specific biophysical properties. A novel explanation is given for conflicting structural determinations.
基金This work was supported by the National Natural Science Foundation of China (Nos. 30470444, 20672106)
文摘The crystal structure of the title compound （C34H47NTO9, Mr = 697.79） has been determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21 with a = 9.000（8）, b = 11.360（10）, c = 17.841（15.）/k, β = 97.083（14）°, V = 1810（3）A^3, Z = 2, F（000） = 744, D,.= 1.280 g/cm^3,/t = 0.094 mm^-1, the final R = 0.0721 and wR = 0.1942 for 2479 observed reflections with I 〉 2σ（I）. The two methyl groups attached to the cyclobutane ring are cis oriented. An intramolecular hydrogen bond （N（6）-H（6）…O（8）） introduces rigidity into the title molecule and the crystal structure is stabilized by intermolecular N-H…O hydrogen bonds.
基金by the National Basic Research Program(973 Program)(Nos.2006CB806503,2007CB914301 and 2007CB914304)the National Programs for High Technology Research and Development Program(863 Program)(No.2006AA02A322)the National Major Project(Grant No.2009ZX10004-304).
文摘The human Gadd45 protein family plays critical roles in DNA repair,negative growth control,genomic stability,cell cycle checkpoints and apoptosis.Here we report the crystal structure of human Gadd45,revealing a unique dimer formed via a bundle of four parallel helices,involving the most conserved residues among the Gadd45 isoforms.Mutational analysis of human Gadd45 identified a conserved,highly acidic patch in the central region of the dimer for interaction with the proliferating cell nuclear antigen(PCNA),p21 and cdc2,suggesting that the parallel dimer is the active form for the interaction.Cellular assays indicate that:(1)dimerization of Gadd45 is necessary for apoptosis as well as growth inhibition,and that cell growth inhibition is caused by both cell cycle arrest and apoptosis;(2)a conserved and highly acidic patch on the dimer surface,including the important residues Glu87 and Asp89,is a putative interface for binding proteins related to the cell cycle,DNA repair and apoptosis.These results reveal the mechanism of self-association by Gadd45 proteins and the importance of this self-association for their biological function.
