ORCID Profile
0000-0001-7521-7587
Current Organisation
Klinikum Wels-Grieskirchen
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Publisher: Proceedings of the National Academy of Sciences
Date: 28-11-2006
Abstract: The molecular basis of the genetic code manifests itself in the interaction of the aminoacyl-tRNA synthetases and their cognate tRNAs. The fundamental biological question regarding these enzymes' role in the evolution of the genetic code remains open. Here we probe this question in a system in which the same tRNA species is aminoacylated by two unrelated synthetases. Should this tRNA possess major identity elements common to both enzymes, this would favor a scenario where the aminoacyl-tRNA synthetases evolved in the context of preestablished tRNA identity, i.e., after the universal genetic code emerged. An experimental system is provided by the recently discovered O -phosphoseryl-tRNA synthetase (SepRS), which acylates tRNA Cys with phosphoserine (Sep), and the well known cysteinyl-tRNA synthetase, which charges the same tRNA with cysteine. We determined the identity elements of Methanocaldococcus jannaschii tRNA Cys in the aminoacylation reaction for the two Methanococcus maripaludis synthetases SepRS (forming Sep-tRNA Cys ) and cysteinyl-tRNA synthetase (forming Cys-tRNA Cys ). The major elements, the discriminator base and the three anticodon bases, are shared by both tRNA synthetases. An evolutionary analysis of archaeal, bacterial, and eukaryotic tRNA Cys sequences predicted additional SepRS-specific minor identity elements (G37, A47, and A59) and suggested the dominance of vertical inheritance for tRNA Cys from a single common ancestor. Transplantation of the identified identity elements into the Escherichia coli tRNA Gly scaffold endowed facile phosphoserylation activity on the resulting chimera. Thus, tRNA Cys identity is an ancient RNA record that depicts the emergence of the universal genetic code before the evolution of the modern aminoacylation systems.
Publisher: Proceedings of the National Academy of Sciences
Date: 20-02-2007
Abstract: A number of archaeal organisms generate Cys-tRNA Cys in a two-step pathway, first charging phosphoserine (Sep) onto tRNA Cys and subsequently converting it to Cys-tRNA Cys . We have determined, at 3.2-Å resolution, the structure of the Methanococcus maripaludis phosphoseryl-tRNA synthetase (SepRS), which catalyzes the first step of this pathway. The structure shows that SepRS is a class II, α 4 synthetase whose quaternary structure arrangement of subunits closely resembles that of the heterotetrameric (αβ) 2 phenylalanyl-tRNA synthetase (PheRS). Homology modeling of a tRNA complex indicates that, in contrast to PheRS, a single monomer in the SepRS tetramer may recognize both the acceptor terminus and anticodon of a tRNA substrate. Using a complex with tungstate as a marker for the position of the phosphate moiety of Sep, we suggest that SepRS and PheRS bind their respective amino acid substrates in dissimilar orientations by using different residues.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.JVIR.2017.09.012
Abstract: To evaluate the diagnostic accuracy of diameter measurements for the detection of aneurysm volume increase during follow-up after endovascular aortic repair (EVAR) of abdominal aortic aneurysms (AAAs). This retrospective study analyzed 100 pairs of follow-up computed tomography scans randomly selected from an EVAR database (male/female ratio, 91/9 mean age, 71 y bifurcated and aortouniiliac stent grafts, 96% and 4%, respectively mean interval, 359 d). Five maximum diameter (D The anteroposterior, transverse, axial, coronal, and perpendicular D Depending on the chosen cutoff value, diameter measurements showed low to moderate sensitivity for the detection of aneurysm volume increase. The diameter measurements failed to detect aneurysm enlargement in a large number of patients with persistent type II endoleak after EVAR of AAA.
No related grants have been discovered for Michael Schnitzbauer.