Crystal structure of a DNA binding protein from the hyperthermophilic euryarchaeon Methanococcus jannaschii.
The Sac10b family consists of a group of highly conserved DNA binding proteins from both the euryarchaeotal and the crenarchaeotal branches of Archaea. The proteins have been suggested to play an architectural role in the chromosomal organization in these organisms. Previous studies have mainly focused on the Sac10b proteins from the crenarchaeota. Here, we report the 2.0 A resolution crystal structure of Mja10b from the euryarchaeon Methanococcus jannaschii. The model of Mja10b has been refined to an R-factor of 20.9%. The crystal structure of an Mja10b monomer reveals an alpha/beta structure of four beta-strands and two alpha-helices, and Mja10b assembles into a dimer via an extensive hydrophobic interface. Mja10b has a similar topology to that of its crenarchaeota counterpart Sso10b (also known as Alba). Structural comparison between the two proteins suggests that structural features such as hydrophobic inner core, acetylation sites, dimer interface, and DNA binding surface are conserved among Sac10b proteins. Structural differences between the two proteins were found in the loops. To understand the structural basis for the thermostability of Mja10b, the Mja10b structure was compared to other proteins with similar topology. Our data suggest that extensive ion-pair networks, optimized accessible surface area and the dimerization via hydrophobic interactions may contribute to the enhanced thermostability of Mja10b.
Wang
Ganggang
G
MOE Laboratory of Protein Science and Laboratory of Structural Biology, Department of Biological Science and Biotechnology, Tsinghua University, Beijing, 100084, People's Republic of China.
Guo
Rong
R
Bartlam
Mark
M
Yang
Haitao
H
Xue
Hong
H
Liu
Yiwei
Y
Huang
Li
L
Rao
Zihe
Z
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry*; D019281:Dimerization; D006860:Hydrogen Bonding; D007477:Ions / Q000737:chemistry; D017017:Methanococcus / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D016415:Sequence Alignment; D013816:Thermodynamics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D007477:Ions