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( Jason M. Park ),( Christian M. Ponder ),( B. Trevor Sewell ),( Michael J. Benedik ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.12
Nitrilases pose attractive alternatives to the chemical hydrolysis of nitrile compounds. The activity of bacterial nitrilases towards substrate is intimately tied to the formation of large spiral-shaped oligomers. In the nitrilase CynD (cyanide dihydratase) from Bacillus pumilus, mutations in a predicted oligomeric surface region altered its oligomerization and reduced its activity. One mutant, CynD Y70C, retained uniform oligomer formation however it was inactive, unlike all other inactive mutants throughout that region all of which significantly perturbed oligomer formation. It was hypothesized that Y70 is playing an additional role necessary for CynD activity beyond influencing oligomerization. Here, we performed saturation mutagenesis at residue 70 and demonstrated that only tyrosine or phenylalanine is permissible for CynD activity. Furthermore, we show that other residues at this position are not only inactive, but have altered or disrupted oligomer conformations. These results suggest that Y70`s essential role in activity is independent of its role in the formation of the spiral oligomer.
Marando, Catherine M.,Park, Choul Yong,Liao, Jason A.,Lee, Jimmy K.,Chuck, Roy S. Wolters Kluwer Health, Inc. All rights reserved. 2017 Cornea Vol.36 No.6
<P>Conclusions: Two-photon excited fluorescence microscopy has improved our understanding of the peripheral corneal architecture. CB tendon insertions in this region may contribute to the radial tears encountered when preparing DM endothelial keratoplasty grafts.</P>
EZH2 Generates a Methyl Degron that Is Recognized by the DCAF1/DDB1/CUL4 E3 Ubiquitin Ligase Complex
Lee, J.,Lee, Jason S.,Kim, H.,Kim, K.,Park, H.,Kim, J.Y.,Lee, S.,Kim, I.,Kim, J.,Lee, M.,Chung, C.,Seo, S.B.,Yoon, J.B.,Ko, E.,Noh, D.Y.,Kim, K.,Kim, K.,Baek, S. Cell Press 2012 Molecular cell Vol.48 No.4
Ubiquitination plays a major role in protein degradation. Although phosphorylation-dependent ubiquitination is well known for the regulation of protein stability, methylation-dependent ubiquitination machinery has not been characterized. Here, we provide evidence that methylation-dependent ubiquitination is carried out by damage-specific DNA binding protein 1 (DDB1)/cullin4 (CUL4) E3 ubiquitin ligase complex and a DDB1-CUL4-associated factor 1 (DCAF1) adaptor, which recognizes monomethylated substrates. Molecular modeling and binding affinity studies reveal that the putative chromo domain of DCAF1 directly recognizes monomethylated substrates, whereas critical binding pocket mutations of the DCAF1 chromo domain ablated the binding from the monomethylated substrates. Further, we discovered that enhancer of zeste homolog 2 (EZH2) methyltransferase has distinct substrate specificities for histone H3K27 and nonhistones exemplified by an orphan nuclear receptor, RORα. We propose that EZH2-DCAF1/DDB1/CUL4 represents a previously unrecognized methylation-dependent ubiquitination machinery specifically recognizing ''methyl degron''; through this, nonhistone protein stability can be dynamically regulated in a methylation-dependent manner.
Choi, Yong Seok,Park, Jin Kyun,Kang, Eun Ha,Lee, Young-Kyun,Kim, Tae Kyun,Chung, Jin-Haeng,Zimmerer, Jason M,Carson III, William E,Song, Yeong Wook,Lee, Yun Jong BioMed Central 2013 ARTHRITIS RESEARCH AND THERAPY Vol.15 No.6
<P><B>Introduction</B></P><P>Although IL-1β is believed to be crucial in the pathogenesis of osteoarthritis (OA), the IL-1β blockade brings no therapeutic benefit in human OA and results in OA aggravation in several animal models. We explored the role of a cytokine signaling 1 (SOCS1) suppressor as a regulatory modulator of IL-1β signaling in chondrocytes.</P><P><B>Methods</B></P><P>Cartilage samples were obtained from patients with knee OA and those without OA who underwent surgery for femur-neck fracture. SOCS1 expression in cartilage was assessed with immunohistochemistry. IL-1β-induced SOCS1 expression in chondrocytes was analyzed with quantitative polymerase chain reaction and immunoblot. The effect of SOCS1 on IL-1β signaling pathways and the synthesis of matrix metalloproteinases (MMPs) and aggrecanase-1 was investigated in SOCS1-overexpressing or -knockdown chondrocytes.</P><P><B>Results</B></P><P>SOCS1 expression was significantly increased in OA cartilage, especially in areas of severe damage (<I>P</I> < 0.01). IL-1β stimulated SOCS1 mRNA expression in a dose-dependent pattern (<I>P</I> < 0.01). The IL-1β-induced production of MMP-1, MMP-3, MMP-13, and ADAMTS-4 (aggrecanase-1, a disintegrin and metalloproteinase with thrombospondin motifs 4) was affected by SOCS1 overexpression or knockdown in both SW1353 cells and primary human articular chondrocytes (all <I>P</I> values < 0.05). The inhibitory effects of SOCS1 were mediated by blocking p38, c-Jun N-terminal kinase (JNK), and nuclear factor κB (NF-κB) activation, and by downregulating transforming growth factor-β-activated kinase 1 (TAK1) expression.</P><P><B>Conclusions</B></P><P>Our results show that SOCS1 is induced by IL1-β in OA chondrocytes and suppresses the IL-1β-induced synthesis of matrix-degrading enzymes by inhibiting IL-1β signaling at multiple levels. It suggests that the IL-1β-inducible SOCS1 acts as a negative regulator of the IL-1β response in OA cartilage.</P>
Walker, Bright,Liu, Jianhua,Kim, Chunki,Welch, Gregory C.,Park, Jin Keun,Lin, Jason,Zalar, Peter,Proctor, Christopher M.,Seo, Jung Hwa,Bazan, Guillermo C.,Nguyen, Thuc-Quyen The Royal Society of Chemistry 2013 ENERGY AND ENVIRONMENTAL SCIENCE Vol.6 No.3
<P>We report a series of solution-processable, small-molecule, donor materials based on an architecture consisting of two diketopyrrolopyrrole (DPP) cores with different aromatic π-bridges between the DPP units and different end-capping groups. In general, this architecture leads to desirable light absorption and electronic levels for donor materials. Out of the compounds investigated, a material with a hydrolyzed dithieno(3,2-<I>b</I>;2′,3′-<I>d</I>)silole (SDT) core and 2-benzofuran (BFu) end capping groups leads to the most favorable properties for solar cells, capable of generating photocurrent up to 800 nm while producing an open-circuit voltage of over 850 mV, indicating a small loss in electrical potential compared to other bulk heterojunction systems. Device properties can be greatly improved through the use of solvent additives such as 2-chloronaphthalene and initial attempts to optimize device fabrication have resulted in power conversion efficiencies upwards of 4%.</P> <P>Graphic Abstract</P><P>A series of small-molecule donor materials based on an architecture consisting of two diketopyrrolopyrrole (DPP) moieties with different core and end groups is reported. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3ee24351f'> </P>