@article{HasnatZupokOlasApeltetal.2021,
  author    = {Hasnat, Muhammad Abrar and Zupok, Arkadiusz and Olas-Apelt, Justyna Jadwiga and M{\"u}ller-R{\"o}ber, Bernd and Leimk{\"u}hler, Silke},
  title     = {A-type carrier proteins are involved in [4Fe-4S] cluster insertion into the radical S-adenosylmethionine protein MoaA for the synthesis of active molybdoenzymes},
  series = {Journal of bacteriology},
  volume    = {203},
  journal   = {Journal of bacteriology},
  number    = {12},
  publisher = {American Society for Microbiology},
  address   = {Washington},
  issn      = {1098-5530},
  doi       = {10.1128/JB.00086-21},
  pages     = {20},
  year      = {2021},
  abstract  = {Iron sulfur (Fe-S) clusters are important biological cofactors present in proteins with crucial biological functions, from photosynthesis to DNA repair, gene expression, and bioenergetic processes. For the insertion of Fe-S clusters into proteins, A-type carrier proteins have been identified. So far, three of them have been characterized in detail in Escherichia coli, namely, IscA, SufA, and ErpA, which were shown to partially replace each other in their roles in [4Fe-4S] cluster insertion into specific target proteins. To further expand the knowledge of [4Fe-4S] cluster insertion into proteins, we analyzed the complex Fe-S cluster-dependent network for the synthesis of the molybdenum cofactor (Moco) and the expression of genes encoding nitrate reductase in E. coli. Our studies include the identification of the A-type carrier proteins ErpA and IscA, involved in [4Fe-4S] cluster insertion into the radical Sadenosyl-methionine (SAM) enzyme MoaA. We show that ErpA and IscA can partially replace each other in their role to provide [4Fe-4S] clusters for MoaA. Since most genes expressing molybdoenzymes are regulated by the transcriptional regulator for fumarate and nitrate reduction (FNR) under anaerobic conditions, we also identified the proteins that are crucial to obtain an active FNR under conditions of nitrate respiration. We show that ErpA is essential for the FNR-dependent expression of the narGHJI operon, a role that cannot be compensated by IscA under the growth conditions tested. SufA does not appear to have a role in Fe-S cluster insertion into MoaA or FNR under anaerobic growth employing nitrate respiration, based on the low level of gene expression. <br /> IMPORTANCE Understanding the assembly of iron-sulfur (Fe-S) proteins is relevant to many fields, including nitrogen fixation, photosynthesis, bioenergetics, and gene regulation. Remaining critical gaps in our knowledge include how Fe-S clusters are transferred to their target proteins and how the specificity in this process is achieved, since different forms of Fe-S clusters need to be delivered to structurally highly diverse target proteins. Numerous Fe-S carrier proteins have been identified in prokaryotes like Escherichia coli, including ErpA, IscA, SufA, and NfuA. In addition, the diverse Fe-S cluster delivery proteins and their target proteins underlie a complex regulatory network of expression, to ensure that both proteins are synthesized under particular growth conditions.},
  language  = {en}
}
@article{YildizLeimkuehler2021,
  author    = {Yildiz, Tugba and Leimk{\"u}hler, Silke},
  title     = {TusA is a versatile protein that links translation efficiency to cell division in Escherichia coli},
  series = {Journal of bacteriology},
  volume    = {203},
  journal   = {Journal of bacteriology},
  number    = {7},
  publisher = {American Society for Microbiology},
  address   = {Washington},
  issn      = {1098-5530},
  doi       = {10.1128/JB.00659-20},
  pages     = {20},
  year      = {2021},
  abstract  = {To enable accurate and efficient translation, sulfur modifications are introduced posttranscriptionally into nucleosides in tRNAs. The biosynthesis of tRNA sulfur modifications involves unique sulfur trafficking systems for the incorporation of sulfur atoms in different nucleosides of tRNA. One of the proteins that is involved in inserting the sulfur for 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U34) modifications in tRNAs is the TusA protein. TusA, however, is a versatile protein that is also involved in numerous other cellular pathways. Despite its role as a sulfur transfer protein for the 2-thiouridine formation in tRNA, a fundamental role of TusA in the general physiology of Escherichia coli has also been discovered. Poor viability, a defect in cell division, and a filamentous cell morphology have been described previously for tusA-deficient cells. In this report, we aimed to dissect the role of TusA for cell viability. We were able to show that the lack of the thiolation status of wobble uridine (U-34) nucleotides present on Lys, Gln, or Glu in tRNAs has a major consequence on the translation efficiency of proteins; among the affected targets are the proteins RpoS and Fis. Both proteins are major regulatory factors, and the deregulation of their abundance consequently has a major effect on the cellular regulatory network, with one consequence being a defect in cell division by regulating the FtsZ ring formation. <br /> IMPORTANCE More than 100 different modifications are found in RNAs. One of these modifications is the mnm(5)s(2)U modification at the wobble position 34 of tRNAs for Lys, Gln, and Glu. The functional significance of U34 modifications is substantial since it restricts the conformational flexibility of the anticodon, thus providing translational fidelity. We show that in an Escherichia coli TusA mutant strain, involved in sulfur transfer for the mnm(5)s(2)U34 thio modifications, the translation efficiency of RpoS and Fis, two major cellular regulatory proteins, is altered. Therefore, in addition to the transcriptional regulation and the factors that influence protein stability, tRNA modifications that ensure the translational efficiency provide an additional crucial regulatory factor for protein synthesis.},
  language  = {en}
}