3u3g

Publication Abstract from PubMed

Metagenome-derived LC11-RNase H1 is a homolog of Sulfolobus tokodaii RNase H1 (Sto-RNase H1). It lacks a C-terminal tail, which is responsible for hyperstabilization of Sto-RNase H1. Sto-RNase H1 is characterized by its ability to cleave not only an RNA/DNA hybrid but also a double-stranded RNA (dsRNA). To examine whether LC11-RNase H1 also exhibits both RNase H and dsRNase activities, LC11-RNase H1 was overproduced in Escherichia coli, purified, and characterized. LC11-RNase H1 exhibited RNase H activity with similar metal ion preference, optimum pH, and cleavage mode of substrate with those of Sto-RNase H1. However, LC11-RNase H1 did not exhibit dsRNase activity at any condition examined. LC11-RNase H1 was less stable than Sto-RNases H1 and its derivative lacking the C-terminal tail (Sto-RNase H1DeltaC6) by 37 and 13 degrees C in T(m) , respectively. To understand the structural bases for these differences, the crystal structure of LC11-RNase H1 was determined at 1.4 A resolution. The LC11-RNase H1 structure is highly similar to the Sto-RNase H1 structure. However, LC11-RNase H1 has two grooves on protein surface, one containing the active site and the other containing DNA-phosphate binding pocket, while Sto-RNase H1 has one groove containing the active site. In addition, LC11-RNase H1 contains more cavities and buried charged residues than Sto-RNase H1. We propose that LC11-RNase H1 does not exhibit dsRNase activity because dsRNA cannot fit to the two grooves on protein surface and that LC11-RNase H1 is less stable than Sto-RNase H1DeltaC6 because of the increase in cavity volume and number of buried charged residues.

Activity, stability, and structure of metagenome-derived LC11-RNase H1, a homolog of Sulfolobus tokodaii RNase H1.,Nguyen TN, Angkawidjaja C, Kanaya E, Koga Y, Takano K, Kanaya S Protein Sci. 2012 Apr;21(4):553-61. doi: 10.1002/pro.2043. Epub 2012 Mar 2. PMID:22389131^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.