Atsushi Terada

Effect of a probiotic formula on intestinal immunoglobulin A production in healthy children

The anti-infectious effect of probiotics has recently been reported and one mechanism may be the non-specific stimulation of immunity. This study was performed to elucidate the influence of a probiotic formula on intestinal microflora and local immunity in healthy children. A follow-up formula containing viable bifidobacteria was given to seven healthy Japanese children (15 to 31 months old) for 21 days. During intake of the formula, the administered strain was detected in feces from five subjects (71%) and total fecal bifidobacteria slightly increased. Fecal levels of total IgA and anti-poliovirus IgA during intake of the formula were significantly higher than those before intake (P < 0.05). The increase in local IgA levels resulting from ingestion of the probiotic formula may contribute to enhancement of the mucosal resistance against gastrointestinal infections.

Identification of nucleotide residues essential for RNase P activity from the hyperthermophilic archaeon Pyrococcus horikoshii OT3

Ribonuclease P (RNase P) is involved in the processing of the 5′ leader sequence of precursor tRNA (pre-tRNA). We have found that RNase P RNA (PhopRNA) and five proteins (PhoPop5, PhoRpp21, PhoRpp29, PhoRpp30, and PhoRpp38) reconstitute RNase P activity with enzymatic properties similar to those of the authentic ribozyme from the hyperthermophilic archaeon Pyrococcus horikoshii OT3. We report here that nucleotides A40, A41, and U44 at helix P4, and G269 and G270 located at L15/16 in PhopRNA, are, like the corresponding residues in Esherichia coli RNase P RNA (M1RNA), involved in hydrolysis by coordinating catalytic Mg2+ ions, and in the recognition of the acceptor end (CCA) of pre-tRNA by base-pairing, respectively. The information reported here strongly suggests that PhopRNA catalyzes the hydrolysis of pre-tRNA in approximately the same manner as eubacterial RNase P RNAs, even though it has no enzymatic activity in the absence of the proteins.

The contribution of peripheral stem-loops to the catalytic activity of archaeal RNase P RNa from Pyrococcus horikoshii OT3

We investigated the contribution of peripheral stem-loops to the catalytic activity of an archaeal RNase P RNA, PhopRNA, from Pyrococcus horikoshii OT3. PhopRNA mutants, in which the stem-loops were individually deleted, were prepared and characterized with respect to precursor tRNA (pre-tRNA) cleavage activity in the presence of five RNase P proteins. All the mutants retained the activity to some extent, indicating that they are moderately implicated in catalysis. Further characterization suggested that the stem-loops serve largely as binding sites for the proteins, and that their interactions are predominantly involved in stabilization of the active conformation of PhopRNA.