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Lever M.A.,University of Aarhus | Rogers K.L.,Rensselaer Polytechnic Institute | Lloyd K.G.,University of Tennessee at Knoxville | Overmann J.,Leibniz Institute DSMZ Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH. | And 4 more authors.
FEMS Microbiology Reviews | Year: 2015

The ability of microorganisms to withstand long periods with extremely low energy input has gained increasing scientific attention in recent years. Starvation experiments in the laboratory have shown that a phylogenetically wide range of microorganisms evolve fitness-enhancing genetic traits within weeks of incubation under low-energy stress. Studies on natural environments that are cut off from new energy supplies over geologic time scales, such as deeply buried sediments, suggest that similar adaptations might mediate survival under energy limitation in the environment. Yet, the extent to which laboratory-based evidence of starvation survival in pure or mixed cultures can be extrapolated to sustained microbial ecosystems in nature remains unclear. In this review, we discuss past investigations on microbial energy requirements and adaptations to energy limitation, identify gaps in our current knowledge, and outline possible future foci of research on life under extreme energy limitation. © FEMS 2015. All rights reserved.

Stehling O.,University of Marburg | Lill R.,University of Marburg | Lill R.,Max Planck Institute For Terrestrische Mikrobiologie
Cold Spring Harbor Perspectives in Biology | Year: 2013

Iron-sulfur (Fe/S) clusters belong to the most ancient protein cofactors in life, and fulfill functions in electron transport, enzyme catalysis, homeostatic regulation, and sulfur activation. The synthesis of Fe/S clusters and their insertion into apoproteins requires almost 30 proteins in the mitochondria and cytosol of eukaryotic cells. This review summarizes our current biochemical knowledge of mitochondrial Fe/S protein maturation. Because this pathway is essential for various extra mitochondrial processes, we then explain how mitochondria contribute to the mechanism of cytosolic and nuclear Fe/S protein biogenesis, and to other connected processes including nuclear DNA replication and repair, telomere maintenance, and transcription. We next describe how the efficiency of mitochondria to assemble Fe/S proteins is used to regulate cellular iron homeostasis. Finally, we briefly summarize a number of mitochondrial "Fe/S diseases" in which various biogenesis components are functionally impaired owing to genetic mutations. The thorough understanding of the diverse biochemical disease phenotypes helps with testing the current working model for the molecular mechanism of Fe/S protein biogenesis and its connected processes. © Cold Spring Harbor Laboratory Press; all rights reserved.

Buckel W.,University of Marburg | Buckel W.,Max Planck Institute For Terrestrische Mikrobiologie
Angewandte Chemie - International Edition | Year: 2013

The thiyl radical of cysteine 272 (C272) in the C-P lyase adds to 5-phosphoribose-1-methylphosphonate to give a covalently bound thiophosphonate radical. Reaction with glycine 32 (G32) of the enzyme yields methane, a glycyl radical, and thiophosphate (see scheme). Intramolecular attack of the 2-OH group leads to 5-phosphoribose-1,2-cyclic-phosphate, whereas the glycyl radical oxidizes the liberated SH group back to the thiyl radical. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Srinivasan V.,University of Marburg | Pierik A.J.,University of Marburg | Pierik A.J.,University of Kaiserslautern | Lill R.,University of Marburg | Lill R.,Max Planck Institute For Terrestrische Mikrobiologie
Science | Year: 2014

The yeast mitochondrial ABC transporter Atm1, in concert with glutathione, functions in the export of a substrate required for cytosolic-nuclear iron-sulfur protein biogenesis and cellular iron regulation. Defects in the human ortholog ABCB7 cause the sideroblastic anemia XLSA/A. Here, we report the crystal structures of free and glutathione-bound Atm1 in inward-facing, open conformations at 3.06- and 3.38-angstrom resolution, respectively. The glutathione binding site includes a residue mutated in XLSA/A and is located close to the inner membrane surface in a large cavity. The two nucleotide-free adenosine 5′-triphosphate binding domains do not interact yet are kept in close vicinity through tight interaction of the two C-terminal a-helices of the Atm1 dimer. The resulting protein stabilization may be a common structural feature of all ABC exporters.

Stehling O.,University of Marburg | Wilbrecht C.,University of Marburg | Lill R.,University of Marburg | Lill R.,Max Planck Institute For Terrestrische Mikrobiologie
Biochimie | Year: 2014

Work during the past 14 years has shown that mitochondria are the primary site for the biosynthesis of iron-sulfur (Fe/S) clusters. In fact, it is this process that renders mitochondria essential for viability of virtually all eukaryotes, because they participate in the synthesis of the Fe/S clusters of key nuclear and cytosolic proteins such as DNA polymerases, DNA helicases, and ABCE1 (Rli1), an ATPase involved in protein synthesis. As a consequence, mitochondrial function is crucial for nuclear DNA synthesis and repair, ribosomal protein synthesis, and numerous other extra-mitochondrial pathways including nucleotide metabolism and cellular iron regulation. Within mitochondria, the synthesis of Fe/S clusters and their insertion into apoproteins is assisted by 17 proteins forming the ISC (iron-sulfur cluster) assembly machinery. Biogenesis of mitochondrial Fe/S proteins can be dissected into three main steps: First, a Fe/S cluster is generated de novo on a scaffold protein. Second, the Fe/S cluster is dislocated from the scaffold and transiently bound to transfer proteins. Third, the latter components, together with specific ISC targeting factors insert the Fe/S cluster into client apoproteins. Disturbances of the first two steps impair the maturation of extra-mitochondrial Fe/S proteins and affect cellular and systemic iron homeostasis. In line with the essential function of mitochondria, genetic mutations in a number of ISC genes lead to severe neurological, hematological and metabolic diseases, often with a fatal outcome in early childhood. In this review we briefly summarize our current functional knowledge on the ISC assembly machinery, and we present a comprehensive overview of the various Fe/S protein assembly diseases. © 2014 Elsevier Masson SAS. All rights reserved.

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