Piendl Wolfgang A., Dr.rer.nat. - Retired
e-mail:wolfgang.piendl@i-med.ac.at
Phone: +43 512 9003-70331 Fax: +43 512 9003-73110
Address: Institute of Medical Chemistry and Biochemistry
Medical University of Innsbruck, Innrain 80-82 A-6020 Innsbruck, Austria
Research Interests
Interaction of ribosomal proteins with rRNA and mRNA
Ribosomal proteins S8, L1 and L10 (as part of the L10/L124 complex) from different (hyper)thermophilic Archaea and Bacteria exhibit a 10- to 100 fold higher affinity to their specific binding sites on rRNA and mRNA compared to that of their mesophilic counterparts. This stronger protein-RNA interaction might make a substantial contribution to the thermal tolerance of ribosomes in thermophilic organisms. Our investigations are focusing on the identification and characterization of those structural features of RNA-binding proteins that modulate the affinity for their specific RNA binding site. Similarly, we are studying the structural elements of the L1-binding site on 23S rRNA and mRNA, that define them as a high or low affinity binding site.
Solution of the structure of the ribosomal 23S rRNA-L10/L124 complex
Ribosomal proteins L10 and L12 (as a pentameric complex L10IL124) and L11 bind to a highly conserved target site in domain II of 23S rRNA, forming a mobile region (“L12 stalk”) which constitutes a part of the “GTPase-associated site of the 50S ribosomal subunit. The structure of this stalk could not be determined as part of the crystal structure of the 50S or 70S ribosome. In close collaboration with a Russian group we are working on the crystallization of the pentameric L10/L124 complex alone and in complex with the specific 23S rRNA target site. The solution of this structure will fill the last major gap in the current model of the ribosome.
Control of ribosomal protein synthesis in mesophilic and thermophilic Archaea
As Bacteria and Eukarya, Archaea have to coordinate the synthesis of about 60 ribosomal proteins with each other and with three rRNAs. Research is focusing on the MvaL1 operon (encoding ribosomal proteins L1, L10 and L12) from mesophilic and thermophilic Methanococcus species. As in Bacteria, regulation of this operon takes place at the level of translation. The regulator protein MvaL1 binds preferentially to its binding site on the 23S rRNA, and, when in excess, binds with a 20-fold lower affinity to its regulatory binding site on its mRNA (a structural mimic of the 23S rRNA binding site) and thus inhibits translation of all three cistrons of the operon. MvaL1 inhibits its own translation before or at the formation of the first peptide bond, but Mval1 does not inhibit the formation of the functional ternary initiation complex. Our data suggest a novel mechanism of translational inhibition that is different from the displacement or entrapment mechanism described for the regulation of ribosomal proteins in Bacteria. Our next aim is to pinpoint exactly the translation step at which MvaL1 inhibits its own synthesis.
Group Members
Postdoc-Dr. D. Shcherbakov
PhD Student -Olga Platonova
Research grants
- "Regulation of synthesis of ribosomal proteins in Archaea", Austrian Science Fund FWF Project P12070-MOB (1997-2000)
- "Interaction of ribosomal proteins with their specific rRNA and mRNA binding sites", Austrian Science Fund FWF Project P14550-GEN (2000-2004)
International Cooperation
- Prof. Dr. M. Garber, Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia; supported by project No I.5, WTZ Austria-Russia
Vorlesungs-&Praktikumsankündigung
1.) Vorlesung "Molekularbiologische Methoden in der Biochemie" (103011)
2.) Praktikum "Molekularbiologische Methoden in der Biochemie" (103012)
Die Vorbesprechung und due Fstlegung der Termine für BEIDE LEHRVERANSTALTUNGEN findet am
MONTAG, den 06. Oktober 2008, um 08.30 UHR
im Raum 617, 6. OG des Biozentrums (ehem. Institut für Medizinische Chemie & Biochemie), Fritz Pregl-Str. 3, statt.
Im Rahmen des Praktikums soll jeder Student ein eigenes kleines Projekt bearbeiten: die Überexpression eines Gens für ein ribosomales Protein aus einem Bakterium oder Archaeon im Wirtsstamm Escherichia coli. Im Rahmen dieses Projektes werden verschiedene Techmiken wie PCR-Reaktion, Klonierung, Transformation von E. coli, Plasmidpräparation, restriktionsanalysen, spezifische radioaktive Markierung von Protein in vivo, Elektrophorese von DNA und Proteinen etc. zur Anwendung gebracht.
Die gleichnamige Vorlesung liefert then theoretischen Hintergrund zu diesem Praktikum. Nach einem allgemeinen Überblick über das "handwerkszeug des Molekulargenetikers (Enzyme, Vektoren, Wirtsstämme) wird besonders auf Techniken zur Überexpression von fremden Genen im Wirtsorganismus Escherichia coli eingegangen.