1i39

<table><tr><td colspan='2'>[[1i39]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1I39 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1I39 FirstGlance]. <br>

</td></tr><tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Ribonuclease_H Ribonuclease H], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.26.4 3.1.26.4] </span></td></tr>

[[https://www.uniprot.org/uniprot/RNH2_ARCFU RNH2_ARCFU]] Endonuclease that specifically degrades the RNA of RNA-DNA hybrids (By similarity).[HAMAP-Rule:MF_00052_A]

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== Publication Abstract from PubMed ==

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.

Structural biochemistry of a type 2 RNase H: RNA primer recognition and removal during DNA replication.,Chapados BR, Chai Q, Hosfield DJ, Qiu J, Shen B, Tainer JA J Mol Biol. 2001 Mar 23;307(2):541-56. PMID:11254381<ref>PMID:11254381</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

<references/>

[[Category: Chai, Q]]

[[Category: Chapados, B R]]

[[Category: Hosfield, D J]]

[[Category: Qiu, J]]

[[Category: Shen, B]]

[[Category: Tainer, J A]]

[[Category: Mixed beta sheet]]