ADP-ribosyl-acceptor hydrolase 3 (ARH3) plays important roles in regulation of poly(ADP-ribosyl)ation, a reversible post-translational modification, and in maintenance of genomic integrity. ARH3 degrades poly(ADP-ribose) to protect cells from poly(ADP-ribose)-dependent cell death, reverses serine mono(ADP-ribosyl)ation, and hydrolyzes -acetyl-ADP-ribose, a product of Sirtuin-catalyzed histone deacetylation. ARH3 preferentially hydrolyzes-linkages attached to the anomeric C1″ of ADP-ribose; however, how ARH3 specifically recognizes and cleaves structurally diverse substrates remains unknown. Here, structures of full-length human ARH3 bound to ADP-ribose and Mg, coupled with computational modeling, reveal a dramatic conformational switch from closed to open states that enables specific substrate recognition. The glutamate flap, which blocks substrate entrance to Mg in the unliganded closed state, is ejected from the active site when substrate is bound. This closed-to-open transition significantly widens the substrate-binding channel and precisely positions the scissile 1″--linkage for cleavage while securing tightly 2″- and 3″-hydroxyls of ADP-ribose. Our collective data uncover an unprecedented structural plasticity of ARH3 that supports its specificity for the 1″--linkage in substrates and Mg-dependent catalysis.

The purposes of the current study were (1) to examine the relationship between social networking service (SNS) dependency and local community engagement among Seoul residents, (2) to test the hypothesis that integrated connectedness to a community storytelling network (ICSN) is positively related to local community engagement, and (3) to investigate the moderating role of ICSN between SNS dependency and local community engagement. The current study is theoretically guided by communication infrastructure theory (CIT). We used online survey data collected during summer 2013 from a sample of 890 SNS users between the ages of 19 and 59 who lived in 25 districts in Seoul. We focused on four variables as local community engagement outcomes: neighborhood belonging, two collective efficacy variables (informal social control and social cohesion), and community activity participation. We found that SNS dependency and ICSN were positively associated with all local community engagement variables. We also identified the moderating role of ICSN between SNS dependency and the two collective efficacy variables. In addition, we found that closed SNSs (e.g., KakaoTalk) are more likely to facilitate community engagement than open SNSs (e.g., Facebook or Twitter).

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been studied for a wide range of applications due to its potential as a transparent electrode. Herein, the use of imidazole and its derivatives as a neutralizing additive for PEDOT:PSS dispersion and in-depth studies of their effects in terms of electrical properties and stability is reported. Although the neutralization in general reduces the electrical conductivity of PEDOT:PSS, the conductivity after imidazole treatment (685.2 S cm 21 ) is higher than that after treatment of other derivatives. Spectroscopic and thermoelectric studies show that the de-doping effect resulted in the conductivity reduction. As a trade-off of the conductivity reduction, greatly enhanced long-term stability and noncorrosive characteristics are obtained after neutralization. The change in sheet resistance of imidazole-treated PEDOT:PSS after 500 h under harsh conditions (85 8C and 85% humidity) is half that of the untreated samples, demonstrating the great enhancement of the stability.

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