Removal and Reconstitution of the Carotenoid Antenna of Xanthorhodopsin

Salinixanthin, a C40-carotenoid acyl glycoside, serves as a light-harvesting antenna in the retinal-based proton pump xanthorhodopsin of Salinibacter ruber. In the crystallographic structure of this protein, the conjugated chain of salinixanthin is located at the protein–lipid boundary and interacts with residues of helices E and F. Its ring, with a 4-keto group, is rotated relative to the plane of the π-system of the carotenoid polyene chain and immobilized in a binding site near the β-ionone retinal ring. We show here that the carotenoid can be removed by oxidation with ammonium persulfate, with little effect on the other chromophore, retinal. The characteristic CD bands attributed to bound salinixanthin are now absent. The kinetics of the photocycle is only slightly perturbed, showing a 1.5-fold decrease in the overall turnover rate. The carotenoid-free protein can be reconstituted with salinixanthin extracted from the cell membrane of S. ruber. Reconstitution is accompanied by restoration of the characteristic vibronic structure of the absorption spectrum of the antenna carotenoid, its chirality, and the excited-state energy transfer to the retinal. Minor modification of salinixanthin, by reducing the carbonyl C=O double bond in the ring to a C-OH, suppresses its binding to the protein and eliminates the antenna function. This indicates that the presence of the 4-keto group is critical for carotenoid binding and efficient energy transfer

A multiplatform approach identifies miR-152-3p as a common epigenetically regulated onco-suppressor in prostate cancer targeting TMEM97

Prostate cancer (PCa) is a major cause of morbidity and mortality in men worldwide. MicroRNAs are globally downregulated in PCa, especially in poorly differentiated tumors. Nonetheless, the underlying mechanisms are still elusive. Herein, using combined analysis of microRNAs expression and genomewide DNA methylation, we aimed to identify epigenetically downregulated microRNAs in PCa.Research Center of Portuguese Oncology Institute of Porto (FB-GEBC-27 and 19-CI-IPOP-2016). JR-C and CSG are supported by FCT- Fundação para a Ciência e Tecnologia PhD fellowships (SFRH/BD/71293/2010 and SFRH/BD/92786/2013), SS is supported by a PhD fellowship IPO/ESTIMA-1 NORTE-01-0145-FEDER-000027, and IG is a research fellow from the strategic funding of FCT (PCT: PEst- UID/DTP/00776/2013 and COMPETE: POCI-01-0145-FEDER-006868). BMC is funded by FCT-Fundação para a Ciência e a Tecnologia (IF/00601/2012)info:eu-repo/semantics/publishedVersio

The effect of regular walks on various health aspects in older people with dementia: protocol of a randomized-controlled trial

<p>Abstract</p> <p>Background</p> <p>Physical activity has proven to be beneficial for physical functioning, cognition, depression, anxiety, rest-activity rhythm, quality of life (QoL), activities of daily living (ADL) and pain in older people. The aim of this study is to investigate the effect of walking regularly on physical functioning, the progressive cognitive decline, level of depression, anxiety, rest-activity rhythm, QoL, ADL and pain in older people with dementia.</p> <p>Methods/design</p> <p>This study is a longitudinal randomized controlled, single blind study. Ambulatory older people with dementia, who are regular visitors of daily care or living in a home for the elderly or nursing home in the Netherlands, will be randomly allocated to the experimental or control condition. Participants of the experimental group make supervised walks of 30 minutes a day, 5 days a week, as part of their daily nursing care. Participants of the control group will come together three times a week for tea or other sedentary activities to control for possible positive effects of social interaction. All dependent variables will be assessed at baseline and after 6 weeks, and 3, 6, 9, 12 and 18 months of intervention.</p> <p>The dependent variables include neuropsychological tests to assess cognition, physical tests to determine physical functioning, questionnaires to assess ADL, QoL, level of depression and anxiety, actigraphy to assess rest-activity rhythm and pain scales to determine pain levels. Potential moderating variables at baseline are: socio-demographic characteristics, body mass index, subtype of dementia, apolipoprotein E (ApoE) genotype, medication use and comorbidities.</p> <p>Discussion</p> <p>This study evaluates the effect of regular walking as a treatment for older people with dementia. The strength of this study is that 1) it has a longitudinal design with multiple repeated measurements, 2) we assess many different health aspects, 3) the intervention is not performed by research staff, but by nursing staff which enables it to become a routine in usual care. Possible limitations of the study are that 1) only active minded institutions are willing to participate creating a selection bias, 2) the drop-out rate will be high in this population, 3) not all participants will be able to perform/understand all tests.</p> <p>Trial registration</p> <p><a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1482">NTR1482</a></p

Structure determination of the cyclohexene ring of retinal in bacteriorhodopsin by solid-state deuterium NMR.

The orientation and conformation of retinal within bacteriorhodopsin of the purple membrane of Halobacterium halobium was established by solid-state deuterium NMR spectroscopy, through the determination of individual chemical bond vectors. The chromophore ([2,4,4,16,16,17,17,17,18,18-2H11]retinal) was specifically deuterium-labeled on the cyclohexene ring and incorporated into the protein. A uniaxially oriented sample of purple membrane patches was prepared and measured at a series of inclinations relative to the spectrometer field. 31P NMR was used to characterize the mosaic spread of the oriented sample, and computer simulations were applied in the analysis of the 2H NMR and 31P NMR spectral line shapes. From the deuterium quadrupole splittings, the specific orientations of the three labeled methyl groups on the cyclohexene ring could be calculated. The two adjacent methyl groups (on C1) of the retinal were found to lie approximately horizontal in the membrane and make respective angles of 94 degrees +/- 2 degrees and 75 degrees +/- 2 degrees with the membrane normal. The third group (on C5) points toward the cytoplasmic side with an angle of 46 degrees +/- 3 degrees. These intramolecular constraints indicate that the cyclohexene ring lies approximately perpendicular to the membrane surface and that it has a (6S)-trans conformation. From the estimated angle of the tilt of the chomophore long axis, it is concluded that the polyene chain is slightly curved downward to the extracellular side of the membrane