调控蛋白CRP和FNR对青霉素G酰化酶基因表达的影响

青霉素G酰化酶的表达受多种因素的调控。利用crp和fnr基因缺陷型菌株研究了葡萄糖阻遏和氧调控的机制。结果表明：FNR对pac表达不起调控作用，CRP对pac基因表达有正调控作用．并且CRP的结合位点位于结构基因上游的DNA序列上。随后，测定结构基因上游调控区的DNA序列，发现可能的CRP蛋白结合位点的同源保守序列为TGTGA。

The Regulation of Penicillin G Acylase Gene(pac) Expression by CRP and FNR

pJL11 and pJL12 were obtained by cloning of crp gene from plasmid pCRP to pOK12 and fnr gene from pFNR to pRK404. pPA4,pPA6,pJL11 + pPA4,pJL11+pPA6 were transformed to E. coli M182(crp-) and pPA4,pPA6,pJL12 + pPA4, to E. coli JRG1728(fnr-), then activities of PAC were measured after fermentation. It can be found that the activities of PAC in E.coli M182(pPA4+pJL11)is more than that in E.coli M182(pPA4),the activities of PAC in E. coli M182(pPA6 + pJL11)is simillar to that in E. coli M182(pPA6). The data indicated that CRP protein activated the expression of pac. About 2. 7kb DNA segment upstream to the pac structure gene was cloned to BM20. It was found that two possible binding sites of CRP protein upstream to pac promoter by DNA sequencing. On the other hand, the activities of PAC in E. coli JRG1728 (pPA4 + pJL12)is simillar to that in E. coli JRG1728 (pPA4), activities of PAC in E. coli JRGl728(pPA6 + pJL12)is simillar to that in E. coli JRG1728(pPA6). The date .indicated that FNR protein is not involved in the expression regulation of the pac gene.