HMf, a DNA-binding protein isolated from the hyperthermophilic archaeon Methanothermus fervidus, is most closely related to histones.
Methanothermus fervidus grows optimally at 83 degrees C. A protein designated HMf (histone M. fervidus) has been isolated from this archaeal hyperthermophile that binds to double-stranded DNA molecules and increases their resistance to thermal denaturation. HMf binding to linear double-stranded DNA molecules of greater than 2 kilobase pairs also increases their electrophoretic mobilities through agarose gels. Visualization of this compaction process by electron microscopy has demonstrated the formation of quasispherical, macromolecular HMf-DNA complexes. HMf is a mixture of approximately equal amounts of two very similar polypeptides designated HMf-1 and HMf-2. Determination of the DNA sequence of the gene encoding HMf-2 (hmfB) has revealed that over 30% of the amino acid residues in HMf-2 are conserved in the consensus sequences derived for eucaryal histones H2A, H2B, H3, and H4. These archaeal polypeptides and eucaryal histones appear therefore to have evolved from a common ancestor and are likely to have related structures and functions.
Sandman
K
K
Department of Microbiology, Ohio State University, Columbus 43210.
Krzycki
J A
JA
Dobrinski
B
B
Lurz
R
R
Reeve
J N
JN
D000595:Amino Acid Sequence; D019843:Archaeal Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000648:ultrastructure; D019605:Euryarchaeota / Q000235:genetics* / Q000378:metabolism; D006657:Histones / Q000235:genetics*; D006358:Hot Temperature; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010957:Plasmids; D012689:Sequence Homology, Nucleic Acid
D019843:Archaeal Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C065108:HMf protein, Archaeal; D006657:Histones