Structure of Bacteriophage T4 RNase H, a 5′ to 3′ RNA–DNA and DNA–DNA Exonuclease with Sequence Similarity to the RAD2 Family of Eukaryotic Proteins

• Published in: Cell 1996-06, Vol.85 (7), p.1101-1112
• Main Authors: Mueser, Timothy C., Nossal, Nancy G., Hyde, C.Craig
• Format: Article
• Language: English
• Subjects: Bacteriophage T4 - chemistry; Bacteriophage T4 - enzymology; Binding Sites - physiology; Crystallography; DNA - metabolism; DNA-Binding Proteins; DNA-Directed DNA Polymerase - chemistry; Endodeoxyribonucleases - chemistry; Exonucleases - chemistry; Fungal Proteins - chemistry; Image Processing, Computer-Assisted; Magnesium - chemistry; Metals - chemistry; Metals - metabolism; Molecular Sequence Data; phage T4; Protein Conformation; Protein Structure, Secondary; Protein Structure, Tertiary; Ribonuclease H - chemistry; RNA - metabolism; RNA-Directed DNA Polymerase - chemistry; Saccharomyces cerevisiae Proteins; Sequence Homology, Amino Acid; Taq Polymerase
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(00)81310-0

Bacteriophage T4 RNase H is a 5′ to 3′ exonuclease that removes RNA primer from the lagging strand of the DNA replication fork and is a member of the RAD2 family of eukaryotic and prokaryotic replication and repair nucleases. The crystal structure of the full-length native form of T4 RNase H has been solved at 2.06 Å resolution in the presence of Mg 2+ but in the absence of nucleic acids. The most conserved residues are clustered together in a large cleft with two Mg 2+ in the proposed active site. This structure suggests the way in which the widely separated conserved regions in the larger nucleotide excision repair proteins, such as human XPG, could assemble into a structure like that of the smaller replication nucleases.