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1. chinaXiv:201605.01474 [pdf]

Protomer Roles in Chloroplast Chaperonin Assembly and Function

Bai, Cuicui; Guo, Peng; Zhao, Qian; Lv, Zongyang; Zhang, Shijia; Gao, Fei; Tian, Zhixi; Liu, Cuimin; Gao, Liyan; Wang, Yingchun; Bai, Cuicui; Guo, Peng; Zhao, Qian; Zhang, Shijia; Wang, Jifeng; Yang, Fuquan; Wang, Jifeng; Yang, Fuquan
Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology

The individual roles of three chloroplast CPN60 protomers (CPN60 alpha, CPN60 beta 1, and CPN60 beta 2) and whether and how they are assembled into functional chaperonin complexes are investigated in Chlamydomonas reinhardtii. Protein complexes containing all three potential subunits were identified in Chlamydomonas, and their co-expression in Escherichia coli yielded a homogeneous population of oligomers containing all three subunits (CPN60 alpha beta 1 beta 2), with a molecular weight consistent with a tetradecameric structure. While homo-oligomers of CPN60 beta could form, they were dramatically reduced when CPN60 alpha was present and homo-oligomers of CPN60 beta 2 were readily changed into hetero-oligomers in the presence of ATP and other protomers. ATP hydrolysis caused CPN60 oligomers to disassemble and drove the purified protomers to reconstitute oligomers in vitro, suggesting that the dynamic nature of CPN60 oligomers is dependent on ATP. Only hetero-oligomeric CPN60 alpha beta 1 beta 2, containing CPN60 alpha, CPN60 beta 1, and CPN60 beta 2 subunits in a 5: 6: 3 ratio, cooperated functionally with GroES. The combination of CPN60 alpha and CPN60 beta subunits, but not the individual subunits alone, complemented GroEL function in E. coli with subunit recognition specificity. Down-regulation of the CPN60 alpha subunit in Chlamydomonas resulted in a slow growth defect and an inability to grow autotrophically, indicating the essential role of CPN60 alpha in vivo.

submitted time 2016-05-12 Hits501Downloads290 Comment 0

2. chinaXiv:201605.00723 [pdf]

Comparative proteomics reveals abnormal binding of ATGL and dysferlin on lipid droplets from pressure overload-induced dysfunctional rat hearts

Li, Linghai; Zhang, Huina; Li, Linghai; Zhang, Huina; Wang, Jifeng; Zhang, Shuyan; Xu, Shimeng; Shu, Qingbo; Yang, Fuquan; Liu, Pingsheng; Wang, Weiyi; Hong, Yun; Zheng, Min; Xu, Shimeng; Shu, Qingbo; Li, Juanfen; Qian, Zongjie;
Subjects: Biology >> Biophysics

Excessive retention of neutral lipids in cardiac lipid droplets (LDs) is a common observation in cardiomyopathy. Thus, the systematic investigation of the cardiac LD proteome will help to dissect the underlying mechanisms linking cardiac steatosis and myocardial dysfunction. Here, after isolation of LDs from normal and dysfunctional Sprague-Dawley rat hearts, we identified 752 heart-associated LD proteins using iTRAQ quantitative proteomic method, including 451 proteins previously unreported on LDs. The most noteworthy finding was the identification of the membrane resealing protein, dysferlin. An analysis of dysferlin truncation mutants indicated that its C2 domain was responsible for its LD localization. Quantitative proteomic results further determined that 27 proteins were increased and 16 proteins were decreased in LDs from post pressure overload-induced dysfunctional hearts, compared with normal hearts. Notably, adipose triacylglycerol lipase (ATGL) was dramatically decreased and dysferlin was substantially increased on dysfunctional cardiac LDs. This study for the first time reveals the dataset of the heart LD proteome in healthy tissue and the variation of it under cardiac dysfunction. These findings highlight an association between the altered LD protein localization of dysferlin and ATGL and myocardial dysfunction.

submitted time 2016-05-05 Hits477Downloads274 Comment 0

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