Activation of a nucleotide-dependent RCK domain requires binding of a cation cofactor to a conserved site

RCK domains regulate the activity of K+ channels and transporters in eukaryotic and prokaryotic organisms by responding to ions or nucleotides. The mechanisms of RCK activation by Ca2+ in the eukaryotic BK and bacterial MthK K+ channels are well understood. However, the molecular details of activation in nucleotide-dependent RCK domains are not clear. Through a functional and structural analysis of the mechanism of ATP activation in KtrA, a RCK domain from the B. subtilis KtrAB cation channel, we have found that activation by nucleotide requires binding of cations to an intra-dimer interface site in the RCK dimer. In particular, divalent cations are coordinated by the ¿-phosphates of bound-ATP, tethering the two subunits and stabilizing the active state conformation. Strikingly, the binding site residues are highly conserved in many different nucleotide-dependent RCK domains, indicating that divalent cations are a general cofactor in the regulatory mechanism of many nucleotide-dependent RCK domains.We thank access to ALBA (XALOC), ESRF (ID23-1) and Soleil (PROXIMA 1 and 2a) synchrotrons and technical support provided by the i3S scientific platform ‘Biochemical and Biophysical Technologies’ and FCUP|DQB-Lab and Services. Work was supported by Fundação Luso-Americana para o Desenvolvimento through the FLAD Life Science 2020 award entitled ‘Bacterial K+ transporters are potential antimicrobial targets: mechanisms of transport and regulation’ and by FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020 - Operational Programme for Competitiveness and Internationalization (POCI), Portugal 2020, and by Portuguese funds through FCT - Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior in the framework of the projects POCI-01–0145-FEDER-029863 (PTDC/BIA-BQM/29863/2017) and ‘Institute for Research and Innovation in Health Sciences’ (POCI-01–0145-FEDER-007274).’ CMT-D was supported by FCT fellowship (SFRH/BD/123761/2016) and FF was supported by FCT fellowship (SFRH/BPD/102753/2014)

Pyrometallurgical Treatment of Apatite Concentrate with the Objective of Rare Earth Element Recovery: Part II

Apatite, Ca5(PO4)3F, is a useful raw material for the production of both elemental phosphorus and phosphoric acid, and the mine tailings present at Luossavaara-Kiirunavaara AB (LKAB) in Kiruna, Sweden, represent a significant potential European source of apatite if upgraded to a concentrate. In the present study, pilot apatite concentrate made from the LKAB tailings has been pyrometallurgically treated using carbon to extract phosphorus without fluxing at temperatures exceeding 1800 °C, with the ultimate objective of recovery of rare earth elements (REEs) from the resulting slag/residue phases. Experimental behavior has been modeled using equilibrium thermodynamic predictions performed using HSC®. A process is proposed, and mass–energy balance presented, for the simultaneous production of P4 and CaC2 (ultimately for acetylene, C2H2, and PVC production) from apatite, producing a lime residue significantly enriched in REEs. Possible implications to kiln-based processing of apatite are also discussed

Information Asymmetries between Parents and Educators in German Childcare Institutions

Economic theory predicts market failure in the market for early childhood education and care (ECEC) due to information asymmetries. We empirically investigate information asymmetries between parents and ECEC professionals in Germany, making use of a unique extension of the German Socio-Economic Panel Study (SOEP). It allows us to compare quality perceptions by parents and pedagogic staff of 734 ECEC institutions which were attended by children in SOEP households. Parents and staff were asked to rate the same quality measures. We detect considerable information asymmetries between these groups which differ across quality measures but little by parental socio-economic background or center characteristics. Our findings imply that information is not readily available to parents, an issue that should be addressed by policy-makers

Continuous Flow Organophosphorus Chemistry

With applications ranging from common laboratory reagents to agrochemical blockbusters, organophosphorus compounds are central to organic chemistry. Flow chemistry and related technologies have opened new perspectives in the many areas of organic chemistry, from methodology to total synthesis in R&D and production, regardless of the final potential industrial application. This review gives an overview of the most recent and significant advances in continuous flow organophosphorus chemistry

Native mass spectrometry goes more native:Investigation of membrane protein complexes directly from SMALPs

Other than more widely used methods, the use of styrene maleic acid allows the direct extraction of membrane proteins from the lipid bilayer into SMALPs keeping it in its native lipid surrounding. Here we present the combined use of SMALPs and LILBID-MS, allowing determination of oligomeric states of membrane proteins of different functionality directly from the native nanodiscs.</p