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Folding mechanism of an extremely thermostable (βα)(8)-barrel enzyme : a high kinetic barrier protects the protein from denaturation

Title data

Carstensen, Linn ; Zoldák, Gabriel ; Schmid, Franz X. ; Sterner, Reinhard:
Folding mechanism of an extremely thermostable (βα)(8)-barrel enzyme : a high kinetic barrier protects the protein from denaturation.
In: Biochemistry. Vol. 51 (24 April 2012) Issue 16 . - pp. 3420-3432.
ISSN 1520-4995
DOI: https://doi.org/10.1021/bi300189f

Official URL: Volltext

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Abstract in another language

HisF, the cyclase subunit of imidazole glycerol phosphate synthase (ImGPS) from Thermotoga maritima, is an extremely thermostable (βα)(8)-barrel protein. We elucidated the unfolding and refolding mechanism of HisF. Its unfolding transition is reversible and adequately described by the two-state model, but 6 weeks is necessary to reach equilibrium (at 25 °C). During refolding, initially a burst-phase off-pathway intermediate is formed. The subsequent productive folding occurs in two kinetic phases with time constants of ~3 and ~20 s. They reflect a sequential process via an on-pathway intermediate, as revealed by stopped-flow double-mixing experiments. The final step leads to native HisF, which associates with the glutaminase subunit HisH to form the functional ImGPS complex. The conversion of the on-pathway intermediate to the native protein results in a 10(6)-fold increase of the time constant for unfolding from 89 ms to 35 h (at 4.0 M GdmCl) and thus establishes a high energy barrier to denaturation. We conclude that the extra stability of HisF is used for kinetic protection against unfolding. In its refolding mechanism, HisF resembles other (βα)(8)-barrel proteins.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: PubMed-ID: 22455619
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors > Professorship Biochemistry - Univ.-Prof. Dr. Franz Xaver Schmid
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Professorship Biochemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors
Result of work at the UBT: No
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 28 Apr 2015 11:01
Last Modified: 28 Apr 2015 11:01
URI: https://eref.uni-bayreuth.de/id/eprint/11164