Constitutive Promoters (Type-B Spacers) (Leftward transcription).

Among the total of 1,075 RpoD holoenzyme-binding sites, 181 are located within type-B spacers upstream of left-side genes and downstream of right-side genes, indicating that these promoters direct leftward transcription. The genes and operons under the control of these 181 promoters were estimated, of which 16 represent putative internal promoters. Descriptions and symbols are as in Table 1. A total of 15 genes encoding transcription factors are indicated by star symbols (*). The essential genes listed in the PEC database are underlined within the operons. The promoter sequence with complete match with the canonical promoter (see Fig. 4) is shown in bold and italic while the promoter sequence with 5-out of-6 match is shown in bold. The spacers including H-NS binding sites are marked as HNS in the spacer column. Total number of genes under the control of these 181 promoters were 290 (1.80 gene per promoter). Among the total of 181 RpoD holoenyme-binding sites, 39 (24%) overlap with the H-NS-binding sites.在总计1075个RpoD全酶结合位点（RpoD holoenzyme-binding sites）中，有181个位于左侧基因上游、右侧基因下游的B型间隔区（type-B spacers）内，表明此类启动子介导向左方向的转录。针对这181个启动子所调控的基因与操纵子（operons）进行了预测分析，其中16个属于推定内部启动子（putative internal promoters）。相关描述与符号规范详见表1。共有15个编码转录因子（transcription factors）的基因以星号（*）标注。PEC数据库（PEC database）中收录的必需基因，在其所在操纵子内以下划线标记。与经典启动子（canonical promoter，详见图4）完全匹配的启动子序列以粗斜体格式显示，而6个碱基中有5个匹配的启动子序列则以粗体格式显示。包含H-NS结合位点（H-NS binding sites）的间隔区在间隔区列中标记为“HNS”。这181个启动子所调控的基因总数为290个，平均每个启动子调控1.80个基因。在总计181个RpoD全酶结合位点中，有39个（占比24%）与H-NS结合位点存在重叠。