Analysis of new target genes isolated from genome analysis : towards development of new antibiotics

我研究了枯草芽孢杆菌生长所必需的两个新基因yycFG和ywlC的功能。该基因产物具有新颖性和必要性，可作为新型抗生素的良好靶点。yycF和yycG：最近有报道称，yycF基因编码一个双组分调节系统的反应调节因子，对细胞生长至关重要，尽管在其控制下的基因尚未被确定（Fabret & Hoch, 1998）。我们还注意到，在构建基因组序列计划中新发现的基因敲除突变库的过程中，枯草芽孢杆菌中yycF调控基因及其同源激酶基因yycG的本质。此外，当YycF调节因子在枯草芽孢杆菌中过量产生时，我们发现迷你细胞的产生和细胞长度的减少。这些观察结果导致发现YycF的过量产生上调了细胞分裂操纵子ftsAZ的P1启动子的表达。此外，YycF蛋白在体外与P1启动子区结合。这些结果清楚地表明，yycF和yycG基因编码的必需双组分调控系统具有调节枯草芽孢杆菌ftsAZ操纵子表达的潜力。ywlC：这个基因属于SUA5家族，在真细菌和酵母中保守，但其功能尚不清楚。由于已知中断突变酵母SUA5基因不能在含有乳酸作为碳源的培养基中生长，我们在枯草芽孢杆菌中测试了YwlC蛋白耗尽的可能性。细胞可以在这种条件下生长，这表明枯草芽孢杆菌ywlC的功能与酵母SUA5不同。有趣的是，我们还发现ywlC的转录受到dna的抑制，而dna是染色体复制起始的关键因子。

I have examined functions of two new genes, yycFG and ywlC, essential for call growth of Bacillus subtilis. The gene products could be good targets for new antibiotics because of their newness and essentiality.1.yycF and yycG : The yycF gene encoding a response regulator of a two-component regulatory system was reported recently to be essential for the cell growth, although genes under their control have yet to be identified (Fabret & Hoch, 1998). We also noted the essential nature of the yycF regulator gene and its cognate kinase gene, yycG, in B.subtilis during the course of construction of a knockout mutant bank of the newly identified genes in the genome sequence project. In addition, we found production of mini-cells and reduction in cell length when the YycF regulator was overproduced in B.subtilis. These observations led to the finding that YycF overproduction up-regulated the expression from the P1 promoter of the cell division operon, ftsAZ. In addition, the YycF protein binds to the P1 promoter region in vitro. These results clearly indicate that the essential two-component regulatory system encoded by yycF and yycG genes has the potential to modulate expression of the ftsAZ operon in B.subtilis.2.ywlC : This gene belongs to the SUA5 family that is conserved in eubacteria and yeast but its function is unknown. As a disruption mutant yeast SUA5 gene is known not to grow in a medium containing lactate as the carbon source, we tested the possibility in B.subtilis under depletion of the YwlC protein. Cells could grow under the condition, suggesting that B.subtilis ywlC functions differently from yeast SUA5. Interestingly, it was also found that transcription of ywlC was repressed by DnaA, a key factor of initiation of chromosome replication.