Energetics of MazG Unfolding in Correlation with Its Structural Features

Igor Drobnak, Anja Korenčič, Remy Loris, Irina Marianovsky, Gad Glaser, Andrej Jamnik, Gorazd Vesnaver, Jurij Lah*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


MazG is a homodimeric α-helical protein that belongs to the superfamily of all-α NTP pyrophosphatases. Its function has been connected to the regulation of the toxin-antitoxin module mazEF, implicated in programmed growth arrest/cell death of Escherichia coli cells under conditions of amino acid starvation. The goal of the first detailed biophysical study of a member of the all-α NTP pyrophosphatase superfamily, presented here, is to improve molecular understanding of the unfolding of this type of proteins. Thermal unfolding of MazG monitored by differential scanning calorimetry, circular dichroism spectroscopy, and fluorimetry at neutral pH in the presence of a reducing agent (dithiothreitol) can be successfully described as a reversible four-state transition between a dimeric native state, two dimeric intermediate states, and a monomeric denatured state. The first intermediate state appears to have a structure similar to that of the native state while the final thermally denatured monomeric state is not fully unfolded and contains a significant fraction of residual α-helical structure. In the absence of dithiothreitol, disulfide cross-linking causes misfolding of MazG that appears to be responsible for the formation of multimeric aggregates. MazG is most stable at pH 7-8, while at pH < 6, it exists in a molten-globule-like state. The thermodynamic parameters characterizing each step of MazG denaturation transition obtained by global fitting of the four-state model to differential scanning calorimetry, circular dichroism, and fluorimetry temperature profiles are in agreement with the observed structural characteristics of the MazG conformational states and their assumed functional role.

Original languageAmerican English
Pages (from-to)63-74
Number of pages12
JournalJournal of Molecular Biology
Issue number1
StatePublished - 11 Sep 2009

Bibliographical note

Funding Information:
This work was supported by the Ministry of Higher Education, Science, and Technology and by the Agency for Research of Republic of Slovenia through Grant Nos. P1-0201 and J1-6653 and by Israel Science Foundation Grant 374/08 awarded to G.G.


  • MazG
  • programmed cell death
  • protein unfolding
  • stability
  • toxin-antitoxin module


Dive into the research topics of 'Energetics of MazG Unfolding in Correlation with Its Structural Features'. Together they form a unique fingerprint.

Cite this