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- Carius, Anke B., et al.
(författare)
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Dynamic pH‐induced conformational changes of the PsbO protein in the fluctuating acidity of the thylakoid lumen
- 2019
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Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 166:1, s. 288-299
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Tidskriftsartikel (refereegranskat)abstract
- The PsbO protein is an essential extrinsic subunit of photosystem II, the pigment–protein complex responsible for light‐driven water splitting. Water oxidation in photosystem II supplies electrons to the photosynthetic electron transfer chain and is accompanied by proton release and oxygen evolution. While the electron transfer steps in this process are well defined and characterized, the driving forces acting on the liberated protons, their dynamics and their destiny are all largely unknown. It was suggested that PsbO undergoes proton‐induced conformational changes and forms hydrogen bond networks that ensure prompt proton removal from the catalytic site of water oxidation, i.e. the Mn4CaO5 cluster. This work reports the purification and characterization of heterologously expressed PsbO from green algae Chlamydomonas reinhardtii and two isoforms from the higher plant Solanum tuberosum (PsbO1 and PsbO2). A comparison to the spinach PsbO reveals striking similarities in intrinsic protein fluorescence and CD spectra, reflecting the near‐identical secondary structure of the proteins from algae and higher plants. Titration experiments using the hydrophobic fluorescence probe ANS revealed that eukaryotic PsbO proteins exhibit acid–base hysteresis. This hysteresis is a dynamic effect accompanied by changes in the accessibility of the protein's hydrophobic core and is not due to reversible oligomerization or unfolding of the PsbO protein. These results confirm the hypothesis that pH‐dependent dynamic behavior at physiological pH ranges is a common feature of PsbO proteins and causes reversible opening and closing of their β‐barrel domain in response to the fluctuating acidity of the thylakoid lumen.
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| 2. |
- Kolsrud, Oscar, et al.
(författare)
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Measured and not estimated glomerular filtration rate should be used to assess renal function in heart transplant recipients.
- 2016
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Ingår i: Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. - : Oxford University Press (OUP). - 1460-2385. ; 31:7, s. 1182-9
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Tidskriftsartikel (refereegranskat)abstract
- In organ transplanted patients, impaired renal function is of major prognostic importance and influences therapeutic decisions. Therefore, monitoring of renal function with glomerular filtration rate (GFR) is of importance, both before and after heart transplantation (HTx). The GFR can be measured directly (mGFR) or estimated (eGFR) with equations based on circulating creatinine or cystatin C levels. However, these equations have not been thoroughly validated in the HTx population.
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| 3. |
- Kolsrud, Oscar, et al.
(författare)
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Renal function and outcome after heart transplantation
- 2018
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Ingår i: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223. ; 155:4, s. 1593-1604.e1
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate whether measured glomerular filtration rate (mGFR) is a risk factor for death and/or end-stage renal disease (ESRD) after heart transplantation (HTx). Methods: All adult patients (n = 416) who underwent HTx between 1988 and 2010 were included. mGFR was performed both preoperatively and postoperatively as annual follow-up. Eight patients received a concomitant kidney transplant (KTx), and 15 underwent late KTx due to chronic renal failure after HTx. Results: The mean drop in mGFR compared with the preoperative value was 12% during the first year after HTx. Preoperative mGFR was not predictive of mortality or ESRD. Older or the use of a ventricular assist device (VAD) were preoperative predictors of death. Long-term survival was significantly worse in the patients who experienced a >25% decrease in mGFR during the first year after transplantation. The need for acute postoperative renal replacement therapy (RRT) was associated with impaired survival but did not predict ESRD among survivors. On multivariable analyses, previous heart surgery, preoperative VAD, and a lower mGFR were all predictors of RRT. In the most recent period, death without previous ESRD was lower, and the only preoperative factors associated with ESRD by multivariable analyses were mechanical ventilation and diabetes mellitus. Conclusions: Pretransplantation mGFR was not predictive of mortality or ESRD after HTx, but necessitated simultaneous or late-stage KTx in this selected population of patients. However, patients with a decrease in >25% mGFR during the first year post-transplantation, as well as early postoperative dialysis-dependent acute renal dysfunction, had a poor prognosis. We suggest that patients with severely impaired kidney function, irrespective of pretransplantation renal function, still should be considered for HTx, but also encourage careful interpretation of our results given the selection bias involved in this population.
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