Evidence of a Thermal Unfolding Dimeric Intermediate for the Escherichia coli Histone-like HU Proteins: Thermodynamics and Structure

Ramstein, Jean; Hervouet, Nadège; Coste, Franck; Zelwer, C.; Oberto, Jacques; Castaing, B.

doi:10.1016/s0022-2836(03)00725-3

Cited by 61 publications

(62 citation statements)

References 66 publications

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“…The secondary structural elements of the HU␣␤ heterodimer are comparable to the previously reported structures of HU homodimers of Thermotoga maritima, Bacillus stearothermophilus, Anabaena, and HU␣␣ of E. coli (16)(17)(18)(19)(20). The superimposition of the structures of the ␣-and the ␤-subunits gives an rms deviation (rmsd) of 0.895 Å per 69 C␣ atoms.…”

Section: Resultssupporting

confidence: 81%

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Spiral structure of Escherichia coli HUαβ provides foundation for DNA supercoiling

Guo

Adhya

2007

Proc. Natl. Acad. Sci. U.S.A.

112

101

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We determined the crystal structure of the Escherichia coli nucleoidassociated HU␣␤ protein by x-ray diffraction and observed that the heterodimers form multimers with octameric units in three potential arrangements, which may serve specialized roles in different DNA transaction reactions. It is of special importance that one of the structures forms spiral filaments with left-handed rotations. A negatively superhelical DNA can be modeled to wrap around this lefthanded HU␣␤ multimer. Whereas the wild-type HU generated negative DNA supercoiling in vitro, an engineered heterodimer with an altered amino acid residue critical for the formation of the left-handed spiral protein in the crystal was defective in the process, thus providing the structural explanation for the classical property of HU to restrain negative supercoils in DNA.HU-multimers ͉ nucleoid ͉ x-ray crystallography

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Section: Resultssupporting

confidence: 81%

“…The two monomers interwind into a dimer as a unit. As reported in the HU homodimers (16)(17)(18)(19)(20), the heterodimers also hold extensive intersubunit hydrophobic interactions. The residues that contribute to the hydrophobic core environment are listed in Fig.…”

Section: Resultsmentioning

confidence: 53%

Spiral structure of Escherichia coli HUαβ provides foundation for DNA supercoiling

Guo

Adhya

2007

Proc. Natl. Acad. Sci. U.S.A.

112

101

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“…The E. coli DNA binding protein HU, which is homologous to HlpA, has been studied extensively in its interaction with DNA. Homotypic dimers of E. coli HU interact with DNA via its binding arms, which resemble the amino acid sequence of S. gallolyticus HlpA (27). These binding arms display an amino acid sequence that contains a typical positively charged heparin-binding site, as proposed by Cardin and Weintraub (4,9), which interacts with negatively charged sulfate or carboxyl groups on heparin chains but may also interact with the negatively charged LTA (42).…”

Section: Discussionmentioning

confidence: 97%

Surface-Exposed Histone-Like Protein A Modulates Adherence of Streptococcus gallolyticus to Colon Adenocarcinoma Cells

Boleij¹,

Schaeps²,

Kleijn

et al. 2009

Infect Immun

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Streptococcus gallolyticus (formerly known as Streptococcus bovis biotype I) is a low-grade opportunistic pathogen which is considered to be associated with colon cancer. It is thought that colon polyps or tumors are the main portal of entry for this bacterium and that heparan sulfate proteoglycans (HSPGs) at the colon tumor cell surface are involved in bacterial adherence during the first stages of infection. In this study, we have shown that the histone-like protein A (HlpA) of S. gallolyticus is a genuine anchorless bacterial surface protein that binds to lipoteichoic acid (LTA) of the gram-positive cell wall in a growth phase-dependent manner. In addition, HlpA was shown to be one of the major heparin-binding proteins of S. gallolyticus able to bind to the HSPG-expressing colon tumor cell lines HCT116 and HT-29. Strikingly, although wild-type levels of HlpA appeared to contribute to adherence, coating of additional HlpA at the bacterial surface resulted in reduced binding to colon tumor cells. This may be explained by the fact that heparan sulfate and LTA compete for the same binding site in HlpA. Altogether, this study implies that HlpA serves as a fine-tuning factor for bacterial adherence.

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“…However, no universal basis of stability has been recognized because the stability of different enzymes has different origins. For this reason, more extensive studies have been performed to elucidate the fundamentals of protein stability in terms of macromolecular interactions based on thermodynamics [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic l‐arabinose isomerases: The effects of divalent metal ions on protein stability at elevated temperatures

et al. 2005

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To gain insight into the structural stability of homologous homo-tetrameric L L-arabinose isomerases (AI), we have examined the isothermal guanidine hydrochloride (GdnHCl)-induced unfolding of AIs from mesophilic Bacillus halodurans (BHAI), thermophilic Geobacillus stearothermophilus (GSAI), and hyperthermophilic Thermotoga maritima (TMAI) using circular dichroism spectroscopy. The GdnHCl-induced unfolding of the AIs can be well described by a two-state reaction between native tetramers and unfolded monomers, which directly confirms the validity of the linear extrapolation method to obtain the intrinsic stabilities of these proteins. The resulting unfolding free energy (DG U ) values of the AIs as a function of temperature were fit to the Gibbs-Helmholtz equation to determine their thermodynamic parameters based on a two-state mechanism. Compared with the stability curves of BHAI in the presence and absence of Mn 2+ , those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (T m ) due to decreased heat capacity (DC p ). Moreover, the extent of difference in DC p between the apo and holo thermophilic AIs is larger than that of BHAI. From these studies, we suggest that the metal dependence of the thermophilic AIs, resulting in the reduced DC p , may play a significant role in structural stability compared to their mesophilic analogues, and that the extent of metal dependence of AI stability seems to be highly correlated to oligomerization.

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Evidence of a Thermal Unfolding Dimeric Intermediate for the Escherichia coli Histone-like HU Proteins: Thermodynamics and Structure

Cited by 61 publications

References 66 publications

Spiral structure of Escherichia coli HUαβ provides foundation for DNA supercoiling

Spiral structure of Escherichia coli HUαβ provides foundation for DNA supercoiling

Surface-Exposed Histone-Like Protein A Modulates Adherence of Streptococcus gallolyticus to Colon Adenocarcinoma Cells

A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic l‐arabinose isomerases: The effects of divalent metal ions on protein stability at elevated temperatures

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