Identification of phosphatidic acid interacting proteins in Ganoderma lingzhi / 生物工程学报

Ganoderma lingzhi is widely recognized as a medicinal basidiomycetes. Triterpene acids (TAs) are the key bioactive medicinal components of G. lingzhi. Our previous studies have shown that phospholipid acid (PA) produced by phospholipase D (PLD) plays a regulatory role in TA synthesis. In order to further elucidate the molecular mechanism how PA regulates TA synthesis in G. lingzhi, PA beads enrichment combined with LC-MS/MS technology was used to identify PA interacting proteins in G. lingzhi. A total of 19 PA interacting proteins were identified, including cytochrome P450 monooxygenase (GL22084), specific protein kinase MAPK (GL23765), catalase and cell surface hydrophobicity-associated protein. GST tagged GL22084 and GL23765 proteins were obtained through gene cloning, heterologous expression, and purification. The interactions between GL22084/GL23765 and PA were verified by GST pull down assay. The identification of PA interacting proteins provides a basis for further understanding the molecular mechanism how PLD-mediated PA signaling molecules regulates the TA synthesis in G. lingzhi. Moreover, the PA interacting proteins identified in this study can also provide clues for the research of PLD/PA signaling pathway in other species.

Combination of mass spectrometry and GST pull-down techniques to study potential interacting protein of PCV2 ORF4 / 生物工程学报

A novel protein encoded by the open reading frame 4 (ORF4) was recently discovered in porcine circovirus type 2 (PCV2). However, little is known about the interaction proteins of ORF4 which hindered better understanding the biological functions of ORF4 in the life cycle of PCV2. In the present study, the ORF4 was inserted into the multiple cloning site of pCMV-N-Flag-GST, yielding recombinant plasmid pCMV-N-Flag-GST-ORF4. The recombinant plasmid was transfected into 293T cells and the intracellular interaction complex of ORF4 were enriched and separated by GST pull-down and SDS-PAGE, sequentially. The potential interacting proteins of PCV2 ORF4 were stained with silver and identified by mass spectrometry (MS). Finally, five candidate ORF4-interacting proteins, including Serine/threonine-protein phosphatase 6 catalytic subunit, alpha cardiac muscle 1, actin, SEC14-like protein 5 and myosin 9 were identified. These results would benefit a better understanding of the biological function of ORF4 in PCV2 infected cells.

Expression and Purification of an N?terminal Fragment of the Cav1.2 Calcium Channel and Characterization of Its Interaction with Calmodulin / 中国医科大学学报

Objective To investigate a method for the purification of the N?terminal peptide fragment(NT)of the myocardial calcium channel Cav1.2,and characterize its interaction with calmodulin(CaM). Methods EscherichiacoliBL?21 cells were transformed with plasmid pGEX?6p?3/NT harboring the NT?GST fusion gene. The cells harboring pGEX?6p?3/NT were cultured and protein expression was induced with isopropyl?β?D?thiogalactoside(IPTG). Then,the GST?NT fusion protein was purified by using glutathione Sepharose 4B(GS?4B)beads. GST was cleaved off with the PreScission protease,and SDS?PAGE was performed to detect the purity and relative molecular weight of the purified peptide. Further, GST pull?down assay was performed to characterize the interaction of the NT peptide with CaM. Results SDS?PAGE analysis showed that the NT peptide was successfully purified,with high purity. Results of the GST pull?down assay showed that the NT peptide could interact with CaM. Conclusion This study establishes a method for the purification of the NT peptide and lays the foundation for further research on the interaction partners and biological functions of NT.

Identification of interaction site of MIC2 with aldolase in Toxoplasma gondii / 中国人兽共患病学报

In this study ,we aim to identify the protein interaction site of microneme protein 2 (MIC2) and aldolase in Toxoplasma gondii .The tryptophan (Trp ,W) at site 767 of carboxyl terminus of MIC2 (MIC2C) was mutated into alanine (Ala ,A) by site-directed mutagenesis to construct plasmid MIC2C W/A/pGEX-4T-1 .The mutant protein GST-MIC2C W/A was expressed in E .coli upon IPTG induction .Glutathione sepharose beads were incubated with GST-MIC2C W/A and GST-MIC2C respectively ,then incubated with tachyzoite lysates ,and bound proteins were eluted using sample buffer .Eluants were resolved by SDS-PAGE and Western blot .A protein band specifically recognized by anti-aldolase antibody was detected in prod-ucts coming from GST pull-down of GST-MIC2C ,but not in pull-down products coming from GST-MIC2C W/A .With muta-tion of MIC2C W767 to A ,MIC2 protein lost the binding ability to aldolase .Tryptophan (W767 ) was the protein interaction site of MIC2 and aldolase in T .gondii .

Studies on The Interactions Between NIRF and P53 / 生物化学与生物物理进展

HEK293 or HeLa cells were transfected by NIRF and, or P53, whole cell extracts andimmunoprecipitates were subjected to SDS-PAGE followed by Western blotting. GST pull-down was carried outto identify the interactions between NIRF and P53. In vitro ubiquitination reaction was carried out to identify P53ubquitinate by NIRF. The results suggested that NIRF could interact with P53 in vivo and in vitro. The results alsoshowed that NIRF could ubiquitinate P53 in vivo and in vitro. The results indicated that NIRF would be a newnegative regulator of P53.