近年发现肺炎链球菌存在青霉素结合蛋白（PBP）突变非依赖耐药，其机制不明。文献报道StkP激酶和CiaR调节蛋白失活后产生PBP突变非依赖耐药，ccn-microRNAs基因可能是CiaR靶基因。我们前期研究发现stkP或ciaR基因敲除后ccn-microRNAs下降并出现耐药，其种子序列能与pbps-mRNAs互补配对。本项目拟确定ccn-microRNAs与Hfqs伴侣蛋白组成复合物并结合pbps-mRNAs后招募RNA外切酶使其降解或抑制翻译、StkP识别β-内酰胺类抗生素SXXK基序并与PhpP磷酸酶组成信号网络调控CiaR磷酸化、磷酸化CiaR与ccn-microRNAs和Hfqs及RNA外切酶基因启动子结合并上调其表达，再用靶基因敲除突变株感染小鼠验证体外实验结果，阐明ccn-microRNAs-Hfqs复合物介导PBP突变非依赖β-内酰胺类抗生素耐药机制及其表达调控网络。

Recent studies found the penicillin-binding protein (PBP) mutation-independent drug resistance of Streptococcus pneumoniae, but its resistance mechanism is unknown. Previous literatues reported that inactivation of StkP kinase and CiaR response regulator of S. pneumoniae caused PBP mutation-independent drug resistance and ccn-microRNAs-encoding genes may be the target genes of CiaR. Our previous study found that knockout of either stkP or ciaR gene of S. pneumoniae resulted in the decrease of ccn-microRNAs and presentation of drug resistance and complementary pairing among the seed sequences in ccn-microRNAs and pbps-mRNAs. Therefore, this research project would confirme that both ccn-microRNAs and Hfqs chaperonin compose complexes that combine with pbps-mRNAs to recruit RNA exonuclease for degradation of pbps-mRNAs or inhibit translation of pbps-mRNAs, StkP recognizes β-lactam antibiotics through its SXXK motif and both StkP and PhpP phosphotase compose a signal network for regulation of CiaR phosphorylation, and phosphorylated CiaR can combine with promotors of ccn-microRNAs, Hfqs and RNA exonuclease encoding genes to up-reguate their expression. All the experimental results in vitro will be further verified using target gene-knockout mutants-infected mice. The aim of this project is to illuminate the ccn-microRNAs-Hfqs mediating PBP mutation-independent drug resistance mechanism and their expression regulation network.