Radical -adenosylmethionine (SAM) enzymes exist in organisms from all kingdoms of life, and all of these proteins generate an adenosyl radical via the homolytic cleavage of the S-C(5') bond of SAM. Of particular interest are radical SAM enzymes, such as heme chaperones, that insert heme into respiratory enzymes. For example, heme chaperones insert heme into target proteins but have been studied only for the formation of cytochrome-type hemoproteins. Here, we report that a radical SAM protein, the heme chaperone HemW from bacteria, is required for the insertion of heme b into respiratory chain enzymes. As other radical SAM proteins, HemW contains three cysteines and one SAM coordinating an [4Fe-4S] cluster, and we observed one heme per subunit of HemW. We found that an intact iron-sulfur cluster was required for HemW dimerization and HemW-catalyzed heme transfer but not for stable heme binding. A bacterial two-hybrid system screen identified bacterioferritins and the heme-containing subunit NarI of the respiratory nitrate reductase NarGHI as proteins that interact with HemW. We also noted that the bacterioferritins potentially serve as heme donors for HemW. Of note, heme that was covalently bound to HemW was actively transferred to a heme-depleted, catalytically inactive nitrate reductase, restoring its nitrate-reducing enzyme activity. Finally, the human HemW orthologue radical SAM domain-containing 1 (RSAD1) stably bound heme. In conclusion, our findings indicate that the radical SAM protein family HemW/RSAD1 is a heme chaperone catalyzing the insertion of heme into hemoproteins.
By now, the term sustainability suffers from being degenerated into a buzzword resulting in an exceptionally large amount and variety of literature. Likely due to this, the dispersal of descriptions, perspectives, and facets regarding sustainability‐assessing methods reveals deficits in terms of theoretical and methodological rigor, novelty, and practical usefulness. Against this background, this article contains an overview of eight selected methods and tools for sustainability assessment. The qualitative review of current research articles concerning energy technologies highlights objectives and purposes, origins, main procedures, fields of application, and examples as well as a critical acclaim for each method. Next to this, several considerations in general such as the role of principles, criteria, and indicators are being illustrated as well as important challenges for measuring sustainability. Thereby, we develop a six‐stage model that supports the choice of an appropriate method for sustainability assessment. In doing so, we derive two fundamental principles, namely “content‐related” features and “performance‐related” features. At the same time, this article underlines the coexistence of various different, highly complex methods, approaches, and perspectives, as well as practical examples to assess sustainability. We evidence an increasing defragmentation and specialization of research on sustainability assessment. Against this background, our findings are likely to foster further theoretical, conceptual, and analytical developments in this research field. This also promotes a customization and the practical value of sustainability assessment methods.
Education is an essential core task of EURECA-PRO and consists of designing and implementing new study programmes at all levels (Bachelor’s, Master’s, and doctoral), developing new, supplementary modules and promoting innovative teaching methods. While spreading and encouraging excellence in learning and teaching is a fundamental part of all higher education institutions, it is especially important for EURECA-PRO in the development of new programmes, courses, and educational concepts across all partner universities. This development presents an opportunity to cement and enhance excellence in teaching and learning across the alliance and to prioritise students’ educational experience.
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