1I39

RNASE HII FROM ARCHAEOGLOBUS FULGIDUS

1I39 の概要

• エントリーDOI: 10.2210/pdb1i39/pdb
• 分子名称: RIBONUCLEASE HII (2 entities in total)
• 機能のキーワード: mixed beta sheet, helix-loop-helix, hydrolase
• 由来する生物種: Archaeoglobus fulgidus
• 細胞内の位置: Cytoplasm (Potential): O29634
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 25393.24

構造登録者

Chapados, B.R.,Chai, Q.,Hosfield, D.J.,Qiu, J.,Shen, B.,Tainer, J.A. (登録日: 2001-02-13, 公開日: 2001-04-11, 最終更新日: 2024-11-20)

主引用文献

Chapados, B.R.,Chai, Q.,Hosfield, D.J.,Qiu, J.,Shen, B.,Tainer, J.A.
Structural biochemistry of a type 2 RNase H: RNA primer recognition and removal during DNA replication.
J.Mol.Biol., 307:541-556, 2001

PubMed Abstract: DNA replication and cellular survival requires efficient removal of RNA primers during lagging strand DNA synthesis. In eukaryotes, RNA primer removal is initiated by type 2 RNase H, which specifically cleaves the RNA portion of an RNA-DNA/DNA hybrid duplex. This conserved type 2 RNase H family of replicative enzymes shares little sequence similarity with the well-characterized prokaryotic type 1 RNase H enzymes, yet both possess similar enzymatic properties. Crystal structures and structure-based mutational analysis of RNase HII from Archaeoglobus fulgidus, both with and without a bound metal ion, identify the active site for type 2 RNase H enzymes that provides the general nuclease activity necessary for catalysis. The two-domain architecture of type 2 RNase H creates a positively charged binding groove and links the unique C-terminal helix-loop-helix cap domain to the active site catalytic domain. This architectural arrangement apparently couples directional A-form duplex binding, by a hydrogen-bonding Arg-Lys phosphate ruler motif, to substrate-discrimination, by a tyrosine finger motif, thereby providing substrate-specific catalytic activity. Combined kinetic and mutational analyses of structurally implicated substrate binding residues validate this binding mode. These structural and mutational results together suggest a molecular mechanism for type 2 RNase H enzymes for the specific recognition and cleavage of RNA in the RNA-DNA junction within hybrid duplexes, which reconciles the broad substrate binding affinity with the catalytic specificity observed in biochemical assays. In combination with a recent independent structural analysis, these results furthermore identify testable molecular hypotheses for the activity and function of the type 2 RNase H family of enzymes, including structural complementarity, substrate-mediated conformational changes and coordination with subsequent FEN-1 activity.

PubMed: 11254381
DOI: 10.1006/jmbi.2001.4494

実験手法

X-RAY DIFFRACTION (1.95 Å)