Y Sano

Alternative splicing isoform of tau protein kinase I/glycogen synthase kinase 3β

Glycogen synthase kinase 3 (GSK3) plays important roles in Wnt and insulin signaling, cell fate determination, and Alzheimer‐like tau phosphorylation. We discovered an isoform of tau protein kinase I (TPKI)/GSK3β with a 13 amino acid insert in the catalytic domain owing to alternative splicing. The alternative transcripts were found in the brains of the mouse, rat and human, with highly conserved sequences. The variant protein, named TPKI2/GSK3β2, was abundant in the brain. Immunohistochemistry indicated differential distribution of the conventional and the new TPKI/GSK3β isoforms within young neurons. TPKI2/GSK3β2 showed decreased kinase activities towards two phosphorylation sites on tau compared with the conventional isoform. Immunohistochemistry indicated that TPKI2/GSK3β2 occurs predominantly in the neuronal soma, while TPKI1/GSK3β1 is found both in the soma and processes. These results indicate that the new splice isoform has a different function. Because the amino acid insert occurs in the domain implicated in interaction with a protein phosphatase in a homologous kinase cdk‐2, the alternative splicing can regulate multiprotein complex formation and function involving TPKI/GSK3β.

The sequence and function of the recA gene and its protein in Pseudomonas aeruginosa PAO.

SummaryThe recA gene of Pseudomonas aeruginosa has been isolated and its nucleotide sequence has been determined. The coding region of the recA gene has 1038 bp specifying 346 amino acids. The recA protein of P. aeruginosa showed a striking homology with that of Escherichia coli except for the carboxy-terminal region both at the nucleotide and amino acid level. The recA+-carrying plasmids restored the UV sensitivity and recombination ability of several rec mutants of P. aeruginosa. The precise location of the recA gene on the chromosome was deduced from the analysis of R′ plasmids.

A novel transposon-like structure carries the genes for pyocin AP41, a Pseudomonas aeruginosa bacteriocin with a DNase domain homology to E2 group colicins

SummaryThe genetic determinant for pyocin AP41, a bacteriocin produced by Pseudomonas aeruginosa, has been cloned. The determinant is located on the chromosome flanked by a pair of inverted repeats, forming a transposon-like structure (TnAP41). TnAP41 possesses some features characteristic of the Tn3 family of transposons. Based on a comparison with the structure of the corresponding region of the chromosome of a nonproducer strain, we propose that P. aeruginosa has acquired pyocinogeny by the transposition of TnAP41 into the chromosome. The determinant comprises two ORFs encoding the protein subunits responsible for the killing action (the large component) and immunity (the small component). Amino acid sequences of the C-terminus of the large component (the deoxyribonuclease domain) and the immunity protein show remarkable homology to those of E2 group colicins, suggesting that these bacteriocins, which are produced by distantly related species, have originated from a common ancestor.

Construction and Characterization of Chimeric Proteins Between Pyocins and Colicin E3

Pyocins S1, S2 and AP41 are the most frequently found protease-sensitive bacteriocins inPseudomonas aeruginosa. They are classified by the different receptor specificities. A peculiar feature of these bacteriocins is that their genetic determinants are all located at definite sites on the the chromosome. This is in sharp contrast to the case of other bacteriocins, such as colicins, which are of plasmid origin. We cloned these pyocin genes on appropriate plasmids and determined their DNA base sequences, and purified their proteins.