大肠杆菌SD序列与基因表达水平的关系

The Relation between Shine-Dalgarno Region and Gene Expression Level in E.coli

依据基因表达水平的理论预测方法从１３７３个大肠杆菌基因中选出了７３个甚高表达基因和１００个甚低表达基因．研究了这两类基因编码区起始密码子ＡＴＧ前－１到－２１位点（包含ＳＤ序列）的碱基构成与基因表达水平的关系．结果表明，ＳＤ序列中的富嘌呤区（约在－７到－１２位点）Ｇ和Ｔ的概率分布曲线中心到ＡＴＧ的距离（记为ＬＨ）与基因表达水平有明显的关系．甚高表达基因ＬＨ约为１０，甚低表达基因的ＬＨ约为８；另外在－１位点处。

Using the self consistent information cluster method,we select 73 very high expressed genes and 100 very low expressed genes from 1 373 E.coli genes and analyze their base distribution of -1 to -21 sites before ATG codon.We find that the base distribution at -1 to -21 sites (including SD region) are correlated to the gene expresseion levels,the distance from ATG to the center of SD region (Shine-Dalgarno region) which corresponding to the position of maximum P (G) and the position of minimum P (T) is increased from 8 bases for very low expressed genes to 10 bases for very high expressed genes. In addition,for very high expressed genes,the probability of base T and base C in site -1 are different from very low expressed genes.