Structural basis of the high thermal stability of the histone-like HU protein from the mollicute Spiroplasma melliferum KC3.
The three-dimensional structure of the histone-like HU protein from the mycoplasma Spiroplasma melliferum KC3 (HUSpm) was determined at 1.4 Å resolution, and the thermal stability of the protein was evaluated by differential scanning calorimetry. A detailed analysis revealed that the three-dimensional structure of the HUSpm dimer is similar to that of its bacterial homologues but is characterized by stronger hydrophobic interactions at the dimer interface. This HUSpm dimer interface lacks salt bridges but is stabilized by a larger number of hydrogen bonds. According to the DSC data, HUSpm has a high denaturation temperature, comparable to that of HU proteins from thermophilic bacteria. To elucidate the structural basis of HUSpm thermal stability, we identified amino acid residues potentially responsible for this property and modified them by site-directed mutagenesis. A comparative analysis of the melting curves of mutant and wild-type HUSpm revealed the motifs that play a key role in protein thermal stability: non-conserved phenylalanine residues in the hydrophobic core, an additional hydrophobic loop at the N-terminal region of the protein, the absence of the internal cavity present at the dimer interface of some HU proteins, and the presence of additional hydrogen bonds between the monomers that are missing in homologous proteins.
Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova pl., 1, Moscow, 123182, Russian Federation.|Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt. 33, bld. 2, 119071, Moscow, Russian Federation.
Konstantin M
KM
Boyko
Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova pl., 1, Moscow, 123182, Russian Federation.|Laboratory of Hormonal Regulation Proteins, M.M. Shemyakin-Yu.A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya, 16/10, Moscow, 117997, Russian Federation.
Tatiana V
TV
Rakitina
Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova pl., 1, Moscow, 123182, Russian Federation.
Dmitry A
DA
Korzhenevskiy
Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova pl., 1, Moscow, 123182, Russian Federation.
Anna V
AV
Vlaskina
Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova pl., 1, Moscow, 123182, Russian Federation.
Yuliya K
YK
Agapova
Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova pl., 1, Moscow, 123182, Russian Federation.
Dmitry E
DE
Kamashev
Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt. 33, bld. 2, 119071, Moscow, Russian Federation.|Koltzov Institute of Developmental Biology, Russian Academy of Sciences. ul. Vavilova, 26, Moscow, 119334, Russian Federation.
Sergey Y
SY
Kleymenov
Kurchatov Complex of NBICS-Technologies, National Research Center "Kurchatov Institute", Akad. Kurchatova pl., 1, Moscow, 123182, Russian Federation.|Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt. 33, bld. 2, 119071, Moscow, Russian Federation.
Vladimir O
VO
Popov
D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics*; D002152:Calorimetry, Differential Scanning; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D055550:Protein Stability; D013149:Spiroplasma / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013816:Thermodynamics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C040330:histone-like protein HU, bacteria