Study on the function and network of Bacillus subtilis transcription factors

研究了枯草芽孢杆菌（Bacillus subtilis）分子中含有HTH基序的转录调控因子以及影响胞外碱性蛋白酶基因aprE表达的转录调控因子。我们采用的策略是，我们首先进行微阵列分析，如果检测到表达水平的任何差异，我们然后使用lacZ基因融合来确认结果。对于转录调节因子AhrC（HTH），我们发现除了该因子的已知靶标外，它还影响pucR的表达，pucR是参与嘌呤降解的基因的负调节因子。还发现AhrC负面影响aprE以及在GlnA控制下的ure操纵子和rgA的表达。由于AhrC、GlnA和AprE似乎在氮源的供应中密切相关，因此可以假设它们在细胞中形成网络。对于ComK（HTH），我们发现了除了参与感受态发育的那些基因之外的许多靶基因，并在编码区上游区域中识别出已知的共有序列。对于含有HTH的AnsR和DeoR，我们无法找到除已知靶点以外的基因。我们还研究了一个双组分系统的调节子YclJ，发现它至少控制三个操纵子。操纵子上游区域的序列比对和缺失分析使我们能够鉴定YclJ结合的共有序列。我们还研究了分子中含有HTH并正调控aptE表达的SenS。结果表明，SenS对aprE表达的抑制剂scoC的转录产生负面影响。此外，我们发现，删除ybaL（salA），其功能是未知的，导致aprE表达的减少，SalA是一个积极的调节scoC表达。

We studied Bacillus subtills transaiptional regulators containing Helix Tum-Helix (HTH) motif in the molecule and those that affect expression of aprE, the gene encoding extracellular alkaline protease. The strategy we adopted was that we fist carried out microarray analysis, and if any difference was detected in expression levels, we then confirmed the result using a lacZ gene fusion. For transaiptional regulator AhrC(HTH), we found that in addition to the known targets of the factor it affected expression of pucR, the negative regulator of the genes involved in purine degradation. It was also found that AhrC negatively affected the expression of aprE and both the ure operon and rgA that are under the control of GlnA. Since it appears that AhrC, GlnA and AprE are closely related in the supply of the nitrogen source, it can be assumed that they form a network in the cell. For ComK(HTH), we found many target genes in addition to those involved in competence development, and recognized the known consensus sequence in the regions upstream of the codng regions. For AnsR and DeoR, which contain HTH, we could not find genes other than their already known targets. We also investigated the regulator, YclJ, of a two-component system, and found that it controls at least three operons. Alignment of the sequences in the upstream regions of the operons and deletion analysis allowed us to identify a consensus sequence to which YclJ binds.We also studied SenS that contains HTH in the molecule and positively regulates aptE expression. It was shown that SenS exerted a negative effect on the transcription of scoC, an inhibitor of aprE expression. Furthermore, we found that a deletion of ybaL (salA) whose function had been unknown resulted in a decrease in aprE expression and that SalA was a positive regulator of scoC expression.