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H Bügl

Publications and source records attributed to H Bügl.

4 recordsLinked to original sources
PubMed2000

RNA methylation under heat shock control.

Structural, biochemical, and genetic techniques were applied to investigate the function of FtsJ, a recently identified heat shock protein. FtsJ is well conserved, from bacteria to humans. The 1.5 A crystal structure of FtsJ in complex with its cofactor S-adenosylmethionine revealed that FtsJ has a methyltransferase fold. The molecular surface of FtsJ exposes a putative nucleic acid binding groove composed of highly conserved, positively charged residues. Substrate analysis showed that FtsJ methylates 23S rRNA within 50S ribosomal subunits in vitro and in vivo. Null mutations in ftsJ show a dramatically altered ribosome profile, a severe growth disadvantage, and a temperature-sensitive phenotype. Our results reveal an unexpected link between the heat shock response and RNA metabolism.

Amino Acid Sequence↗
PubMed1996

Chaperone function of Hsp90-associated proteins.

The Hsp90 heat shock protein of eukaryotic cells regulates the activity of proteins involved in signal transduction pathways and may direct intracellular protein folding in general. Hsp90 performs at least part of its function in a complex with a specific set of partner proteins that include members of the prolyl isomerase family. The properties of the major components of the Hsp90 complex were examined through the use of in vitro protein folding assays. Two of the components, FKBP52 and p23, functioned as mechanistically distinct molecular chaperones. These results suggest the existence of a super-chaperone complex in the cytosol of eukaryotic cells.

Amino Acid Isomerases↗
PubMed1995

Structural organization of procaryotic and eucaryotic Hsp90. Influence of divalent cations on structure and function.

Hsp90 is a very abundant molecular chaperone that apparently helps to protect cellular proteins from denaturation upon temperature upshift. The unusual ability of Hsp90 to function under conditions where other proteins unfold prompted us to investigate the stability and structural organization of Hsp90 itself. Both procaryotic and eucaryotic members of the Hsp90 family were found to have very similar physicochemical properties: (i) they are stable against thermal unfolding up to at least 50 degrees C, (ii) they show biphasic, reversible unfolding transitions in guanidinium chloride, and (iii) their oligomerization state is strongly and rapidly affected by millimolar concentrations of divalent cations. In the presence of MnCl2 and MgCl2 defined changes in the quaternary structure of Hsp90 could be observed which resulted in a decrease in thermostability and an increased tendency to form larger aggregates. The addition of divalent cations also almost completely abolished the chaperone function of Hsp90 and induced release of folding intermediates of citrate synthase bound to Hsp90. These modulating effects of divalent cations on structure and function of Hsp90 in vitro represent a potential mechanism for regulation of Hsp90 chaperone action in vivo.

Animals↗