Eukaryotic RNases H1 act processively by interactions through the duplex RNA-binding domain

Ribonucleases H have mostly been implicated in eliminating short RNA primers used for initiation of lagging strand DNA synthesis. Escherichia coli RNase HI cleaves these RNA–DNA hybrids in a distributive manner. We report here that eukaryotic RNases H1 have evolved to be processive enzymes by attaching a duplex RNA-binding domain to the RNase H region. Highly conserved amino acids of the duplex RNA-binding domain are required for processivity and nucleic acid binding, which leads to dimerization of the protein. The need for a processive enzyme underscores the importance in eukaryotic cells of processing long hybrids, most of which remain to be identified. However, long RNA–DNA hybrids formed during immunoglobulin class-switch recombination are potential targets for RNase H1 in the nucleus. In mitochondria, where RNase H1 is essential for DNA formation during embryogenesis, long hybrids may be involved in DNA replication

RNases H1 surface plasmon resonance analysis () RNases H1 of mouse, human, and sequence alignment are shown

<p><b>Copyright information:</b></p><p>Taken from "Eukaryotic RNases H1 act processively by interactions through the duplex RNA-binding domain"</p><p>Nucleic Acids Research 2005;33(7):2166-2175.</p><p>Published online 14 Apr 2005</p><p>PMCID:PMC1079969.</p><p>© The Author 2005. Published by Oxford University Press. All rights reserved</p> Numbering refers to the mouse protein. Mouse and human RNases H1 mitochondrial localization signals are underlined. The methionine at the start of the protein used in these studies is marked by an inverted solid triangle and amino acids W43, K59 and K60, marked by an asterisk, are the amino acids that were changed to A for RNase H1, RNase H1 and RNase H1. RNase H (RNase H domain, gold background) starts at amino acid 137 and ends at amino acid 285. The dsRHbd sequences are on a green background with the positions of the α helices (red boxes) and β strands (blue boxes) of RNase H1 first dsRHbd noted below the dsRHbd sequences. For the sequence, amino acids in α helices are red and β strands are blue. Increase in protein bound to duplex RNAs as a function of protein concentration. Some of the sensograms from which these data were obtained are presented in Supplementary Figure S1. Wild-type mouse RNase H1 data are represented by a solid black circle, RNase HI by a solid black square, RNase H1 by an inverted solid black triangle, RNase H1 by an open circle, RNase H1 by an inverted open triangle and RNase H1 by a solid black diamond. () and () are from data collected with the 12 bp RNA–DNA hairpin hybrid while the surface in () is a 12 bp RNA–RNA hairpin duplex RNA of the same sequence as the 12 bp RNA–DNA hybrid. The lack of binding of mouse RNase H1 to the dsRNA at 10 mM MgCl is indicated in (d) by the open square. Nucleic acid sequences of the hairpin duplexes are shown above in (b–d) with RNA in lower case and DNA in upper case letters. Bio-T indicates the biotin modified dT to which the nucleic acid was attached to the streptavidin on the chip surface

Analysis of Outcomes in Ischemic vs Nonischemic Cardiomyopathy in Patients With Atrial Fibrillation A Report From the GARFIELD-AF Registry

IMPORTANCE Congestive heart failure (CHF) is commonly associated with nonvalvular atrial fibrillation (AF), and their combination may affect treatment strategies and outcomes