Comparative study on tertiary contacts and folding of RNase P RNAs from a psychrophilic, a mesophilic/radiation-resistant, and a thermophilic bacterium.

In most bacterial type A RNase P RNAs (P RNAs), two major loop-helix tertiary contacts (L8-P4 and L18-P8) help to orient the two independently folding S- and C-domains for concerted recognition of precursor tRNA substrates. Here, we analyze the effects of mutations in these tertiary contacts in P RNAs from three different species: (i) the psychrophilic bacterium (), (ii) the mesophilic radiation-resistant bacterium () and (iii) the thermophilic bacterium (). We show by UV melting experiments that simultaneous disruption of these two interdomain contacts has a stabilizing effect on all three P RNAs.

Characterization of RNase P RNA activity.

The principle task of the ubiquitous enzyme RNase P is the generation of mature tRNA 5'-ends by removing precursor sequences from tRNA primary transcripts (Trends Genet 19:561-569, 2003; Crit Rev Biochem Mol Biol 41:77-102, 2006; Trends Biochem Sci 31:333-341, 2006). In Bacteria, RNase P is a ribonucleoprotein composed of two essential subunits: a catalytic RNA subunit (P RNA; 350-400 nt) and a single small protein cofactor (P protein; ∼14 kDa). In vitro, bacterial P RNA can catalyze tRNA maturation in the absence of the protein cofactor at elevated concentrations of mono- and divalent cations (Cell 35:849-857, 1983).

A new approach to phenotyping disseminated tumor cells: methodological advances and clinical implications.

At the time of primary therapy (surgery, systemic chemotherapy and/or radiation), disseminated tumor cells in the bone marrow can be found in almost one-third of patients with cancer of the breast, ovary, esophagus, stomach, colon, and other solid tumors. Whereas the prognostic impact of the mere presence of these cells is still a matter of debate, it has been shown that expression of tumor-associated antigens in disseminated tumor cells is linked to more aggressive disease. Therefore, further characterization of disseminated tumor cells at the protein and gene level has become increasingly important.

CD87-positive tumor cells in bone marrow aspirates identified by confocal laser scanning fluorescence microscopy.

Dissemination of single tumor cells to the bone marrow is a common event in cancer. The clinical significance of cytokeratin-positive cells detected in the bone marrow of cancer patients is still a matter of debate. In gastric cancer, overexpression of the receptor (uPAR or CD87) for the serine protease urokinase-type plasminogen activator (uPA) in disseminated cancer cells indicates shorter survival of cancer patients.