DNA binding and cleavage by the HNH homing endonuclease I-HmuI.
The structure of I-HmuI, which represents the last family of homing endonucleases without a defining crystallographic structure, has been determined in complex with its DNA target. A series of diverse protein structural domains and motifs, contacting sequential stretches of nucleotide bases, are distributed along the DNA target. I-HmuI contains an N-terminal domain with a DNA-binding surface found in the I-PpoI homing endonuclease and an associated HNH/N active site found in the bacterial colicins, and a C-terminal DNA-binding domain previously observed in the I-TevI homing endonuclease. The combination and exchange of these features between protein families indicates that the genetic mobility associated with homing endonucleases extends to the level of independent structural domains. I-HmuI provides an unambiguous structural connection between the His-Cys box endonucleases and the bacterial colicins, supporting the hypothesis that these enzymes diverged from a common ancestral nuclease.
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. A3-025, Seattle, WA 98109, USA.
Betty W
BW
Shen
Markus
M
Landthaler
David A
DA
Shub
Barry L
BL
Stoddard
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D003087:Colicins / Q000737:chemistry; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000737:chemistry* / Q000378:metabolism*; D008670:Metals / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D003087:Colicins; D008670:Metals; D004247:DNA; D003850:Deoxyribonuclease I