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Articles by Jianping Ding
Total Records ( 4 ) for Jianping Ding
  Meiling Zhang , Tao Gui , Yunsheng Li , Chao Wei , Nian Zhan , Zhen Chen , Yuanliang Zhang , Ya Liu , Qing Jia , Jianping Ding , Xiaorong Zhang and Yunhai Zhang
  This study was conducted to explore efficient and cost-effective protocols for isolation and culture of mammary epithelial cells from goats during gestation period (non-lactating). Tissues collected from the mammary glands of a Huanghuai white goat, at gestation day 60 were cultured in the presence of fetal bovine serum, insulin-transferrin-selenium and epidermal growth factor. Cell lines were purified using differential enzyme digestion, high density cultivation and continuous passaging. And subsequently characterized by immunofluorescence staining, cell growth curve, oil red O staining and karyotype analysis. In conclusion, a goat mammary epithelial cell line was successfully established and shown to exhibit normal conformation, growth characteristics and lactation function by using improved sample collection and in vitro culture methods. This study provides a new and efficient cell culture protocol, which may facilitate research into the development and function of goat mammary glands and the development of bioreactors.
  Shuai Chen , Tiancen Hu , Jian Zhang , Jing Chen , Kaixian Chen , Jianping Ding , Hualiang Jiang and Xu Shen
  SARS-CoV 3C-like protease (3CLpro) is an attractive target foranti-severe acute respiratory syndrome (SARS) drug discovery,and its dimerization has been extensively proved to be indispensablefor enzymatic activity. However, the reason why the dissociatedmonomer is inactive still remains unclear due to the absenceof the monomer structure. In this study, we showed that mutationof the dimer-interface residue Gly-11 to alanine entirely abolishedthe activity of SARS-CoV 3CLpro. Subsequently, we determinedthe crystal structure of this mutant and discovered a completecrystallographic dimer dissociation of SARS-CoV 3CLpro. Themutation might shorten the α-helix A` of domain I and cause amis-oriented N-terminal finger that could not correctly squeezeinto the pocket of another monomer during dimerization, thusdestabilizing the dimer structure. Several structural featuresessential for catalysis and substrate recognition are severelyimpaired in the G11A monomer. Moreover, domain III rotates dramaticallyagainst the chymotrypsin fold compared with the dimer, fromwhich we proposed a putative dimerization model for SARS-CoV3CLpro. As the first reported monomer structure for SARS-CoV3CLpro, the crystal structure of G11A mutant might provide insightinto the dimerization mechanism of the protease and supply directstructural evidence for the incompetence of the dissociatedmonomer.
  Tiancen Hu , Dalei Wu , Jing Chen , Jianping Ding , Hualiang Jiang and Xu Shen
  The meso-diaminopimelate decarboxylase (DAPDC, EC 4.1.1.2[EC]0) catalyzes the final step of L-lysine biosynthesis in bacteria and is regarded as a target for the discovery of antibiotics. Here we report the 2.3Å crystal structure of DAPDC from Helicobacter pylori (HpDAPDC). The structure, in which the product L-lysine forms a Schiff base with the cofactor pyridoxal 5'-phosphate, provides structural insight into the substrate specificity and catalytic mechanism of the enzyme, and implies that the carboxyl to be cleaved locates at the si face of the cofactor. To our knowledge, this might be the first reported external aldimine of DAPDC. Moreover, the active site loop of HpDAPDC is in a "down" conformation and shields the ligand from solvent. Mutations of Ile148 from the loop greatly impaired the catalytic efficiency. Combining the structural analysis of the I148L mutant, we hypothesize that HpDAPDC adopts an induced-fit catalytic mechanism in which this loop cycles through "down" and "up" conformations to stabilize intermediates and release product, respectively. Our work is expected to provide clues for designing specific inhibitors of DAPDC.
  Bingfa Sun , Jing Hong , Peng Zhang , Xianchi Dong , Xu Shen , Donghai Lin and Jianping Ding
  Eaf3 is a component of both NuA4 histone acetyltransferase and Rpd3S histone deacetylase complexes in Saccharomyces cerevisiae. It is involved in the regulation of the global pattern of histone acetylation that distinguishes promoters from coding regions. Eaf3 contains a chromo domain at the N terminus that can bind to methylated Lys-36 of histone H3 (H3K36). We report here the crystal structures of the Eaf3 chromo domain in two truncation forms. Unlike the typical HP1 and Polycomb chromo domains, which contain a large groove to bind the modified histone tail, the Eaf3 chromo domain assumes an autoinhibited chromo barrel domain similar to the human MRG15 chromo domain. Compared with other chromo domains, the Eaf3 chromo domain contains a unique 38-residue insertion that folds into two short β-strands and a long flexible loop to flank the β-barrel core. Both isothermal titration calorimetry and surface plasmon resonance studies indicate that the interaction between the Eaf3 chromo domain and the trimethylated H3K36 peptide is relatively weak, with a KD of ~10-4 M. NMR titration studies demonstrate that the methylated H3K36 peptide is bound to the cleft formed by the C-terminal α-helix and the β-barrel core. Site-directed mutagenesis study and in vitro binding assay results show that the conserved aromatic residues Tyr-23, Tyr-81, Trp-84, and Trp-88, which form a hydrophobic pocket at one end of the β-barrel, are essential for the binding of the methylated H3K36. These results reveal the molecular mechanism of the recognition and binding of the methylated H3K36 by Eaf3 and provide new insights into the functional roles of the Eaf3 chromo domain.
 
 
 
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