Replication of the hepadnavirus DNA genome is accomplished via reverse transcription of an intermediate, pregenomic RNA molecule. This process is likely to be carried out by a virally encoded, multifunctional polymerase which possesses DNA- and RNA-dependent DNA polymerase and RNase H activities. However, the nature of the product(s) of the polymerase gene predicted to mediate these functions i...

The absB locus of Streptomyces coelicolor encodes a homolog of bacterial RNase III. We cloned and overexpressed the absB gene product and purified a decahistidine-tagged version of the protein. We show here that AbsB is active against double-stranded RNA transcripts derived from synthetic DNAs but is inactive with single-stranded homopolymers. We thus designate the absB product RNase IIIS. Usin...

Human pancreatic ribonuclease (HP-RNase) has considerable promise as a therapeutic agent. Structure-function analyses of HP-RNase have been impeded by the difficulty of obtaining the enzyme from its host. Here, a gene encoding HP-RNase was designed, synthesized, and inserted into two expression vectors that then direct the production of HP-RNase in Saccharomyces cerevisiae (fused to either an u...

Gametophytic self-incompatibility (GSI) is controlled by a complex S locus containing the pistil determinant S-RNase and pollen determinant SFB/SLF. Tight linkage of the pistil and pollen determinants is necessary to guarantee the self-incompatibility (SI) function. However, multiple probable pollen determinants of apple and Japanese pear, SFBBs (S locus F-box brothers), exist in each S haploty...

Ribonucleoproteins (RNP) are involved in many essential processes in life. However, the roles of RNA and protein subunits in an RNP complex are often hard to dissect. In many RNP complexes, including the ribosome and the Group II introns, one main function of the protein subunits is to facilitate RNA folding. However, in other systems, the protein subunits may perform additional functions, and ...

Mao, G. 2018. Investigation of RNase P active site residues and catalytic domain interaction. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1623. 58 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-513-0214-0. RNase P is an essential endoribonuclease responsible for the maturation of the tRNA 5’end. The RNase P family encompasses the...

Mercaptopurine and thioguanine are anticancer and immunosuppressive agents that exert their primary cytotoxic effects via incorporation of deoxythioguanosine (dG(s)) into DNA, but the precise mechanism(s) by which this causes cytotoxicity remains unknown. We initially determined that the level of dG(s) incorporation into DNA of human T- and B-lineage leukemia cell lines did not correlate signif...

Dimeric proteins can arise by the swapping of structural domains between monomers. The prevalence of this occurrence is unknown. Ribonuclease A (RNase A) is assumed to be a monomer near physiological conditions. Here, this hypothesis is tested and found to be imprecise. The two histidine residues (His12 and His119) in the active site of RNase A arise from two domains (S-peptide and S-protein) o...

A single RNase H enzyme was detected in extracts of Streptococcus pneumoniae. The gene encoding this enzyme was cloned and expressed in Escherichia coli, as demonstrated by its ability to complement a double-mutant rnhA recC strain. Sequence analysis of the cloned DNA revealed an open reading frame of 290 codons that encodes a polypeptide of 31.9 kDa. The predicted protein exhibits a low level ...