Febs Letters

doi: 10.1016/S0014-5793(15)00783-8pmid: N/A

van Maarschalkerweerd, Andreas; Vetri, Valeria; Vestergaard, Bente

doi: 10.1016/j.febslet.2015.08.013pmid: 26297828

Oligomeric species formed during α‐synuclein fibrillation are suggested to be membrane‐disrupting agents, and have been associated with cytotoxicity in Parkinson's disease. The majority of studies, however, have revealed that the effect of α‐synuclein oligomers is only noticeable on systems composed of anionic lipids, while the more physiologically relevant zwitterionic lipids remain intact. We present experimental evidence for significant morphological changes in zwitterionic membranes containing cholesterol, induced by α‐synuclein oligomers. Depending on the lipid composition, model membranes are either unperturbed, disrupt, or undergo dramatic morphological changes and segregate into structurally different components, which we visualize by 2‐photon fluorescence microscopy and generalized polarization analysis using the fluorescent probe Laurdan. Our results highlight the crucial role of cholesterol for mediating interactions between physiologically relevant membranes and α‐synuclein.

Klimanova, Elizaveta A.; Petrushanko, Irina Yu.; Mitkevich, Vladimir A.; Anashkina, Anastasia A.; Orlov, Sergey N.; Makarov, Alexander A.; Lopina, Olga D.

doi: 10.1016/j.febslet.2015.08.011pmid: 26297827

Ion pump, Na,K‐ATPase specifically binds cardiotonic steroids (CTS), which leads to inhibition of the enzyme activity and activation of signaling network in the cell. We have studied interaction of Na,K‐ATPase with CTS of two different types – marinobufagenin and ouabain. We have shown that both CTS inhibit activity of Na,K‐ATPase with the sameK i values, but binding of ouabain is sensitive to the conformation of Na,K‐ATPase while binding of marinobufagenin is not. Furthermore, binding of ouabain and marinobufagenin results in different structural changes in Na,K‐ATPase. Our data allow to explain the diversity of effects on the receptor function of Na,K‐ATPase caused by different types of CTS.

Kawai, Akito; Higuchi, Shigesada; Tsunoda, Masaru; Nakamura, Kazuo T.; Yamagata, Yuriko; Miyamoto, Shuichi

doi: 10.1016/j.febslet.2015.08.019pmid: 26318717

Uracil–DNA glycosylases (UDGs) excise uracil from DNA by catalyzing theN‐glycosidic bond hydrolysis. Here we report the first crystal structures of an archaeal UDG (stoUDG). Compared with other UDGs,stoUDG has a different structure of the leucine‐intercalation loop, which is important for DNA binding. ThestoUDG–DNA complex model indicated that Leu169, Tyr170, and Asn171 in the loop are involved in DNA intercalation. Mutational analysis showed that Tyr170 is critical for substrate DNA recognition. These results indicate that Tyr170 occupies the intercalation site formed after the structural change of the leucine‐intercalation loop required for the catalysis.

Li, Yan; Wong, Yun Xuan; Poh, Zhi Ying; Wong, Ying Lei; Lee, Michelle Yueqi; Ng, Hui Qi; Liu, Boping; Hung, Alvin W.; Cherian, Joseph; Hill, Jeffrey; Keller, Thomas H.; Kang, CongBao

doi: 10.1016/j.febslet.2015.07.044

Inagaki, Koya; Satoh, Tadashi; Yagi-Utsumi, Maho; Le Gulluche, Anne-Charlotte; Anzai, Takahiro; Uekusa, Yoshinori; Kamiya, Yukiko; Kato, Koichi

doi: 10.1016/j.febslet.2015.07.041pmid: 26272828

Protein disulfide isomerase functions as a folding catalyst in the endoplasmic reticulum. Itsb′ anda′ domains provide substrate‐binding sites and undergo a redox‐dependent domain rearrangement coupled to an open–closed structural change. Here we determined the first solution structure of thea′ domain in its oxidized form and thereby demonstrate that oxidation of thea′ domain induces significant conformational changes not only in the vicinity of the active site but also in the distalb′‐interfacial segment. Based on these findings, we propose that this conformational transition triggers the domain segregation coupled with the exposure of the hydrophobic surface.

Zarei, Adel; Trobacher, Christopher P.; Shelp, Barry J.

doi: 10.1016/j.febslet.2015.08.005pmid: 26296314

The last step of polyamine catabolism involves the oxidation of 3‐aminopropanal or 4‐aminobutanal via aminoaldehyde dehydrogenase. In this study, two apple (Malus x domestica)AMADH genes were selected (MdAMADH1 andMdAMADH2) as candidates for encoding 4‐aminobutanal dehydrogenase activity. Maximal activity and catalytic efficiency were obtained with NAD+ and 3‐aminopropanal, followed by 4‐aminobutanal, at pH 9.8. NAD+ reduction was accompanied by the production of GABA and β‐alanine, respectively, when 4‐aminobutanal and 3‐aminopropanal were utilized as substrates.MdAMADH2 was peroxisomal andMdAMADH1 cytosolic. These findings shed light on the potential role of apple AMADHs in 4‐aminobutyrate and β‐alanine production.

Farrow, Scott C.; Facchini, Peter J.

doi: 10.1016/j.febslet.2015.07.042pmid: 26264169

Opium poppy (Papaver somniferum) produces several pharmacologically important benzylisoquinoline alkaloids including the vasodilator papaverine. Pacodine and palaudine are tri‐O‐methylated analogs of papaverine, which contains fourO‐linked methyl groups. However, the biosynthetic origin of pacodine and palaudine has not been established. Three members of the 2‐oxoglutarate/Fe2+‐dependent dioxygenases (2ODDs) family in opium poppy display widespreadO‐dealkylation activity on several benzylisoquinoline alkaloids with diverse structural scaffolds, and two are responsible for the antepenultimate and ultimate steps in morphine biosynthesis. We report a novel 2ODD from opium poppy catalyzing the efficient substrate‐ and regio‐specific 7‐O‐demethylation of papaverine yielding pacodine. The occurrence of papaverine 7‐O‐demethylase (P7ODM) expands the enzymatic scope of the 2ODD family in opium poppy and suggests an unexpected biosynthetic route to pacodine.

Fujikawa, Makoto; Sugawara, Kanako; Tanabe, Tsutomu; Yoshida, Masasuke

doi: 10.1016/j.febslet.2015.08.006pmid: 26297831

Mitochondrial ATP synthase is a motor enzyme in which a central shaft rotates in the stator casings fixed with the peripheral stator stalk. When expression ofd‐subunit, a stator stalk component, was knocked‐down, human cells could not form ATP synthase holocomplex and instead accumulated two subcomplexes, one containing a central rotor shaft plus catalytic subunits (F1‐c‐ring) and the other containing stator stalk components (“b–e–g” complex). F1‐c‐ring was also formed when expression of mitochondrial DNA‐codeda‐subunit and A6L was suppressed. Thus, the central rotor shaft and the stator stalk are formed separately and they assemble later. Similar assembly strategy has been known for ATP synthase of yeast andEscherichia coli and could be common to all organisms.

Jiang, Jing; Zhang, Hao; Lu, Xun; Lu, Yue; Cuneo, Matthew J.; O'Neill, Hugh M.; Urban, Volker; Lo, Cynthia S.; Blankenship, Robert E.

doi: 10.1016/j.febslet.2015.07.039pmid: 26241331

The peridinin‐chlorophylla‐protein (PCP) is one of the major light harvesting complexes (LHCs) in photosynthetic dinoflagellates. We analyzed the oligomeric state of PCP isolated from the dinoflagellateSymbiodinium, which has received increasing attention in recent years because of its role in coral bleaching. Size‐exclusion chromatography (SEC) and small angle neutron scattering (SANS) analysis indicated PCP exists as monomers. Native mass spectrometry (native MS) demonstrated two oligomeric states of PCP, with the monomeric PCP being dominant. The trimerization may not be necessary for PCP to function as a light‐harvesting complex.