Woodbury Robyn L, Wang Xin, Moran Charles P
Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Res Microbiol. 2006 Nov;157(9):851-6. doi: 10.1016/j.resmic.2006.07.002. Epub 2006 Aug 18.
Although not thought to become competent for DNA uptake, the bacterium Streptococcus pyogenes appears to encode within its genome the DNA uptake and recombination machinery required for competence. The promoters of these genes contain a conserved sequence, CIN-box, which is recognized by the S. pyogenes alternative RNA polymerase sigma factor X. Using microarray technology, we found that sigma X induced the expression of competence genes in S. pyogenes. Real-time RT-PCR was performed to confirm that the expression of these transcripts was induced 2-265-fold by sigma X. Of the eight CIN-box loci induced, femB, the ortholog a virulence factor in Staphylococcus aureus, was shown to be transcribed in vitro by RNA polymerase containing sigma X, indicating that sigma X directly activates expression of this CIN-box gene. Sigma X-dependent induction of genes encoding competence machinery in S. pyogenes raises the possibility that some strains of this human pathogen can develop competence for genetic transformation.
虽然化脓性链球菌不被认为具有摄取DNA的能力，但它似乎在其基因组中编码了实现感受态所需的DNA摄取和重组机制。这些基因的启动子包含一个保守序列，即CIN框，它可被化脓性链球菌的替代RNA聚合酶σ因子X识别。利用微阵列技术，我们发现σ因子X可诱导化脓性链球菌中感受态基因的表达。进行实时逆转录PCR以确认这些转录本的表达被σ因子X诱导了2至265倍。在诱导的8个CIN框位点中，金黄色葡萄球菌毒力因子的直系同源基因femB，在体外被含σ因子X的RNA聚合酶转录，这表明σ因子X直接激活了这个CIN框基因的表达。化脓性链球菌中编码感受态机制的基因受σ因子X的依赖性诱导，这增加了这种人类病原体的某些菌株能够发展出遗传转化感受态的可能性。
