Mutation in fission yeast phosphatidylinositol 4-kinase Pik1 is synthetically lethal with defect in telomere protection protein Pot1.

Fission yeast Pik1p is one of three phosphatidylinositol 4-kinases associated with the Golgi complex, but its function is not fully understood. Deletion of pot1+ causes telomere degradation and chromosome circularization. We searched for the gene which becomes synthetically lethal with pot1Δ. We obtained a novel pik1 mutant, pik1-1, which is synthetically lethal with pot1Δ. We found phosphoinositol 4-phosphate in the Golgi was reduced in pik1-1. To investigate the mechanism of the lethality of the pot1Δ pik1-1 double mutant, we constructed the nmt-pot1-aid pik1-1 strain, where Pot1 function becomes low by drugs, which leads to telomere loss and chromosome circularization, and found pik1-1 mutation does not affect telomere resection and chromosome circularization. Thus, our results suggest that pik1+ is required for the maintenance of circular chromosomes.

Alicyclobacillus cellulosilyticus sp. nov., a thermophilic, cellulolytic bacterium isolated from steamed Japanese cedar chips from a lumbermill.

A thermophilic bacterium, strain Sueoka(T), was isolated from steamed Japanese cedar chips from a lumber mill in Gobo, Japan. The strain was able to grow on carboxymethyl cellulose at 60 °C, was Gram-stain-negative, and grew between 40.0 and 67.5 °C (optimum at 55 °C) and between pH 3.5 and 6.5 (optimum at pH 4.8). Comparative analysis of 16S rRNA gene sequences revealed 91.9 , 90.9 , and 90.8% similarity to Alicyclobacillus macrosporangiidus(T), Alicyclobacillus pomorum(T), and Alicyclobacillus acidocaldarius(T), respectively. The major quinone was MK-7 and the predominant cellular fatty acids were ω-cyclohexane C19 : 0 and ω-cyclohexane C17 : 0. The DNA G+C content was 60.8 mol%. Based on the results of this study, strain Sueoka(T) is a novel species of the genus Alicyclobacillus, and the namehttp://dx.doi.org/10.1601/nm.5071Alicyclobacillus cellulosilyticus sp. nov. (type strain Sueoka(T)  = JCM 18487(T)  = KCTC 33007(T)) is proposed.