RNase P is the enzyme that removes 5' extensions from tRNA precursors. With its diversity of enzyme forms-either protein- or RNA-based, ranging from single polypeptides to multi-subunit ribonucleoproteins-the RNase P enzyme family represents a unique model system to compare the evolution of enzymatic mechanisms. Here we present a comprehensive study of substrate recognition and cleavage-site se...

The widely accepted model for the processing of tRNAs in Escherichia coli involves essential initial cleavages by RNase E within polycistronic transcripts to generate pre-tRNAs that subsequently become substrates for RNase P. However, recently we identified two polycistronic tRNA transcripts whose endonucleolytic processing was solely dependent on RNase P. Here we show that the processing of th...

Background Access to appropriate images of fetal brain can greatly assist to diagnose of probable abnormalities. The aim of this study was to compare the suitability of T2-True Fast Imaging with Steady State Free Precession (T2-TRUFI), and T2-Half-Fourier Acquisition Single-Shot Turbo Spin-Echo (T2- HASTE( magnetic resonance imaging (MRI) to extract the fetal brain using the level set algorithm...

Background Frequent blood transfusion is often associated with iron overload. Proper use of iron chelators to treat iron overload requires an accurate measurement of iron levels. Magnetic resonance T2-star (T2* MRI) can measure iron level in the heart and liver. Our goal was to see whether an association exists between serum ferritin level and T2* MRI in patients with major beta thalassemia. ...

It has been suggested that Alba, a well-established chromatin protein in Archaea, is also a subunit of the archaeal RNase P holoenzyme, based on the observation that the homolog of this protein in humans has been shown to be associated with RNase P activity. Using the same biochemical methods we used previously to show that four other proteins homologous to eukaryotic RNase P proteins are bona ...

Phylogenetic studies of yeast nuclear RNase P RNA genes have shown a striking conservation of secondary structure for the Saccharomyces and Schizosaccharomyces RNase P RNAs, yet much of the primary sequence and many substructures vary among the RNAs examined. To investigate which sequences and structural features can be varied and still allow function in a heterologous organism, RNase P genes f...