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Thermal and conformational stability of Ssh10b protein from archaeon Sulfolobus shibattae.

ABSTRACT: The secondary structure of the DNA binding protein Ssh10b is largely unaffected by change in temperature between 25 degrees C and 85 degrees C, indicating that the protein is highly thermostable. Here, we report the temperature-dependent equilibrium denaturation of Ssh10b in the presence of guanidine hydrochloride (GdnHCl). It was found that the transition midpoint values of the temperature (T(m)), and changes of enthalpy (DeltaH(m)) and entropy (DeltaS(m)) of Ssh10b unfolding were linearly decreasing with increasing GdnHCl concentration. The true values of the thermodynamic parameters, T(m)=402 K, DeltaH(m)=590+/-40 kJ x mol(-1) and DeltaS(m)=1.4+/-0.15 kJ x T(-1) x mol(-1), were obtained by linear extrapolation to 0 M GdnHCl. The value of the heat capacity change of Ssh10b unfolding, DeltaC(p)=3.8+/-0.2 kJ x T(-1) x mol(-1) (approx. 19 J T(-1) x mol residue(-1)), was obtained from the measured thermodynamic parameters. This is significantly smaller than that of the average value for mesophilic proteins (50 J.K(-1) x mol residue(-1)) or the value calculated from the Ssh10b structural data (64 J T(-1) x mol residue(-1)). A consequence of the small DeltaC(p) is that the DeltaG of Ssh10b is larger than that of mesophilic proteins, while the values of DeltaH and T*DeltaS are smaller. The small DeltaC(p) of Ssh10b appears to result mainly from the presence of compactness in the denatured state.

SUBMITTER: Xu S

PROVIDER: S-EPMC1182282 | biostudies-literature | 2004 Sep

REPOSITORIES: biostudies-literature

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Thermal and conformational stability of Ssh10b protein from archaeon Sulfolobus shibattae.

Xu Su S Qin Sanbo S Pan Xian-Ming XM

The Biochemical journal 20040901 Pt 2

The secondary structure of the DNA binding protein Ssh10b is largely unaffected by change in temperature between 25 degrees C and 85 degrees C, indicating that the protein is highly thermostable. Here, we report the temperature-dependent equilibrium denaturation of Ssh10b in the presence of guanidine hydrochloride (GdnHCl). It was found that the transition midpoint values of the temperature (T(m)), and changes of enthalpy (DeltaH(m)) and entropy (DeltaS(m)) of Ssh10b unfolding were linearly decr ...[more]

PMID: 15107015

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Project description:We investigated the interaction between Sulfolobus spindle-shaped virus (SSV9) and its native archaeal host Sulfolobus islandicus. We show that upon exposure to SSV9, S. islandicus strain RJW002 has a significant growth delay where the majority of cells are dormant (viable but not growing) for 24 to 48 hours postinfection (hpi) compared to the growth of controls without virus. We demonstrate that in this system, dormancy (i) is induced by both active and inactive virus particles at a low multiplicity of infection (MOI), (ii) is reversible in strains with active CRISPR-Cas immunity that prevents the establishment of productive infections, and (iii) results in dramatic and rapid host death if virus persists in the culture even at low levels. Our results add a new dimension to evolutionary models of virus-host interactions, showing that the mere presence of a virus induces host cell stasis and death independent of infection. This novel, highly sensitive, and risky bet-hedging antiviral response must be integrated into models of virus-host interactions in this system so that the true ecological impact of viruses can be predicted and understood. Viruses of microbes play key roles in microbial ecology; however, our understanding of viral impact on host physiology is based on a few model bacteria that represent a small fraction of the life history strategies employed by hosts or viruses across the three domains that encompass the microbial world. We have demonstrated that rare and even inactive viruses induce dormancy in the model archaeon S. islandicus. Similar virus-induced dormancy strategies in other microbial systems may help to explain several confounding observations in other systems, including the surprising abundance of dormant cell types found in many microbial environments, the difficulty of culturing microorganisms in the laboratory, and the paradoxical virus-to-host abundances that do not match model predictions. A more accurate grasp of virus-host interactions will expand our understanding of the impact of viruses in microbial ecology.

Dataset Information

Thermal and conformational stability of Ssh10b protein from archaeon Sulfolobus shibattae.

Publications

Thermal and conformational stability of Ssh10b protein from archaeon Sulfolobus shibattae.

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