Disease relevance of ECs0210

• Folding of ribonuclease HI from Escherichia coli populates a kinetic intermediate detectable by stopped-flow circular dichroism [1].
• Based upon the seemingly contradictory structural observations of one divalent metal bound to Escherichia coli RNase HI and two divalent metals bound to the HIV RNase H domain, two models explaining RNase H metal dependence have been proposed: a one-metal mechanism and a two-metal mechanism [2].
• The folding kinetics of the N-terminal domain of RNase HI and the N-terminal domain of the ribosomal protein L9 from Escherichia coli (eNTL9) were compared to the previously characterized N-terminal domain of L9 from Bacillus stearothermophilus (bNTL9) [3].
• A Moloney murine leukemia virus (Mo-MLV) Gag-Escherichia coli RNase HI fusion has a strong antiviral effect when used prophylactically, inhibiting the spread of Mo-MLV and reducing virus titers 1,500- to 2,500-fold [4].
• Stabilization of ribonuclease HI from Thermus thermophilus HB8 by the spontaneous formation of an intramolecular disulfide bond [5].

High impact information on ECs0210

• Two RNases H of mammalian tissues have been described: RNase HI, the activity of which was found to rise during DNA replication, and RNase HII, which may be involved in transcription [6].
• By using highly purified calf thymus RNase HI we identified the sequences of several tryptic peptides [6].
• We have determined that a functional gene coding for ribonuclease H seems to be essential for cell growth in Escherichia coli [7].
• Co-crystal of Escherichia coli RNase HI with Mn2+ ions reveals two divalent metals bound in the active site [8].
• We have now solved the co-crystal structure of E. coli RNase HI with Mn(2+) ions at 1.9-A resolution [8].

Chemical compound and disease context of ECs0210

• Role of histidine 124 in the catalytic function of ribonuclease HI from Escherichia coli [9].
• The handle region (residues 84-99) in ribonuclease HI (RNase HI) from Escherichia coli, which is rich in basic amino acid residues, was altered by alanine-scanning mutagenesis [10].
• Previous structural studies revealed a single Mg(2+) ion-binding site in Escherichia coli RNase HI [8].
• Thermostabilization of Escherichia coli ribonuclease HI by replacing left-handed helical Lys95 with Gly or Asn [11].
• To simplify the 1H NMR spectra, two fully deuterated enzymes bearing several protonated amino acids were prepared from an RNase HI overproducing strain of E. coli grown in an almost fully deuterated medium [12].

Biological context of ECs0210

• Thermal stability of Escherichia coli ribonuclease HI and its active site mutants in the presence and absence of the Mg2+ ion. Proposal of a novel catalytic role for Glu48 [13].
• The enzymatic and physicochemical properties as well as the thermal and conformational stabilities of the enzyme were compared with those of E. coli RNase HI, which shows 52% amino acid sequence identity [14].
• Conformational stabilities of Escherichia coli RNase HI variants with a series of amino acid substitutions at a cavity within the hydrophobic core [15].
• Retroviral RNases H are similar in sequence and structure to Escherichia coli RNase HI and yet have differences in substrate specificities, metal ion requirements, and specific activities [16].
• To understand how ribonucleases H recognize RNA-DNA hybrid substrates, we analyzed kinetic parameters of binding of Escherichia coli RNase HI to RNA-DNA hybrids ranging in length from 18 to 36 base pairs (bp) using surface plasmon resonance (BIAcoreTM) [17].

Anatomical context of ECs0210

• 30S ribosomal subunits, 70S ribosomes or polysomes from E. coli were subjected to mild ultraviolet irradiation, and the 3'-terminal region of the 16S RNA was excised by 'addressed cleavage' using ribonuclease H in the presence of suitable complementary oligodeoxynucleotides [18].
• We have previously shown that the overproduction of RNase HI, an enzyme that degrades the RNA portion of an R-loop, can partially compensate for the growth defects because of the absence of topoisomerase I. In this article, we have studied the effects of gyrase reactivation on the physiology of actively growing topA null cells [19].
• Effect of ribonuclease H from chick embryo on the covalent-linked poly(A)--poly(dA) complementary to poly(dT) template [20].

Associations of ECs0210 with chemical compounds

• This priming reaction of primase is verified by a number of biochemical methods, including inhibition by modified 3'-phosphate of oligonucleotides and deoxyribonuclease I and ribonuclease H cleavages [21].
• Identification of single Mn(2+) binding sites required for activation of the mutant proteins of E.coli RNase HI at Glu48 and/or Asp134 by X-ray crystallography [22].
• 1H NMR studies of deuterated ribonuclease HI selectively labeled with protonated amino acids [12].
• A Gly residue inserted between alpha-helices B and C appears to relieve unfavorable interactions in the transition state and alternate conformer(s) and represents an important adaptation to adjust conformational changes within RNase H for activity at high temperatures [23].

Other interactions of ECs0210

• To date, structure/function studies have focused on two members of this family: Escherichia coli RNase HI, a small monomeric protein; and human immunodeficiency virus, type I (HIV) RNase H, a domain of HIV reverse transcriptase [24].
• To facilitate the studies on a recognition mechanism of Abeta by pitrilysin, an overproduction system of Abeta(1-40) as a fusion protein with E. coli RNase HI was constructed [25].

Analytical, diagnostic and therapeutic context of ECs0210

• The role of the conserved histidine residue (His124) in the catalytic function of Escherichia coli ribonuclease HI was probed by the use of the pH titration experiments with 1H NMR and site-directed mutagenesis [9].
• Kinetic and stoichiometric analysis for the binding of Escherichia coli ribonuclease HI to RNA-DNA hybrids using surface plasmon resonance [17].
• Northern blot analysis shows that the cells have a significantly reduced ability to accumulate full-length mRNAs when RNase HI is not overproduced [19].
• Pressure denaturation of Escherichia coli ribonuclease HI (RNase HI) was studied by Fourier transform infrared (FTIR) and two-dimensional NMR spectroscopy at pD* 3.0 and 25 degrees C. A reversible transition in the pressure range of 0.1-1090 MPa was observed with second-derivative FTIR experiments [26].
• Analytical ultracentrifugation studies indicate that the acid state of RNase H is both compact and monomeric [27].

References