SummaryLeishmania major aquaglyceroporin (LmjAQP1) adventitiously facilitates the uptake of antimonite [Sb(III)], an active form of Pentostam® or Glucantime®, which are the first line of defence against all forms of leishmaniasis. The present paper shows that LmjAQP1 activity is modulated by the mitogenactivated protein kinase, LmjMPK2. Leishmania parasites coexpressing LmjAQP1 and LmjMPK2 show increased Sb(III) uptake and increased Sb(III) sensitivity. When subjected to a hypo-osmotic stress, these cells show faster volume recovery than cells expressing LmjAQP1 alone. LmjAQP1 is phosphorylated in vivo at Thr-197 and this phosphorylation requires LmjMPK2 activity. Lys-42 of LmjMPK2 is critical for its kinase activity. Cells expressing altered T197A LmjAQP1 or K42A LmjMPK2 showed decreased Sb(III) influx and a slower volume recovery than cells expressing wild-type proteins. Phosphorylation of LmjAQP1 led to a decrease in its turnover rate affecting LmjAQP1 activity. Although LmjAQP1 is localized to the flagellum of promastigotes, upon phosphorylation, it is relocalized to the entire surface of the parasite. Leishmania mexicana promastigotes with an MPK2 deletion showed reduced Sb(III) uptake and slower volume recovery than wild-type cells. This is the first report where a parasite aquaglyceroporin activity is post-translationally modulated by a mitogen-activated protein kinase.

In the light of the global search for novel and sustainable protein sources, macroalgal proteins are becoming an attractive target. To date, mainly red and green macroalgae have been investigated in this respect, whereas the brown species are less studied, possibly because of the lower content of protein. In a biorefinery context, however, the protein content of brown macroalgae can still be economically interesting due to fast growth and the possibility to co-extract other compounds, such as alginates. The aim of this study was to develop a simple, scalable pH shift-based protein isolation technique applicable on wet Saccharina latissima biomass. Factors investigated were extraction volume, temperature, protein solubilization pH, osmoshock pretreatment and protein precipitation pH. Maximum protein solubility was obtained at pH 12, where 34 % of the total protein content could be extracted with 5.56 volumes of extraction solution (20 volumes on dry weight (dw) basis). Osmoshocking significantly increased the yield, and 20, 40 and 60 volumes of water (dw basis) gave 45.1, 46.8 and 59.5 % yield, respectively. The temperature during osmoshocking did not significantly affect the extraction yield, and extended time (16 vs. 1 or 2 h) reduced protein yield. Precipitation of solubilized proteins was possible below pH 4; the highest precipitation yield, 34.5 %, was obtained at pH 2. After combined alkaline extraction and acid precipitation, 16.01 % of the Saccharina proteins were recovered, which can be considered acceptable in comparison to other studies on algae but leaves some room for improvement when compared to protein extraction from, for instance, soy.

This study monitored the biomass composition of

The Saccharomyces cerevisiae High-Osmolarity Glycerol (HOG) pathway is a conserved mitogen-activated protein kinase (MAPK) signal transduction system that often serves as a model to analyze systems level properties of MAPK signaling. Hog1, the MAPK of the HOG-pathway, can be activated by various environmental cues and it controls transcription, translation, transport, and cell cycle adaptations in response to stress conditions. A powerful means to study signaling in living cells is to use kinase inhibitors; however, no inhibitor targeting wild-type Hog1 exists to date. Herein, we describe the design, synthesis, and biological application of small molecule inhibitors that are cell-permeable, fast-acting, and highly efficient against wild-type Hog1. These compounds are potent inhibitors of Hog1 kinase activity both in vitro and in vivo. Next, we use these novel inhibitors to pinpoint the time of Hog1 action during recovery from G1 checkpoint arrest, providing further evidence for a specific role of Hog1 in regulating cell cycle resumption during arsenite stress. Hence, we describe a novel tool for chemical genetic analysis of MAPK signaling and provide novel insights into Hog1 action.

TY13 could be a promising future starter culture for fermented foods with improved mineral bioavailability. Using strains that secrete phytase to the food matrix may significantly improve the phytate degradation by facilitating the enzyme-to-substrate interaction. The secreted non-cell-bound phytase activities by TY13 could further be advantageous in industrial production of phytase.