分子伴侣GroEL对青霉素G酰化酶亚基折叠的影响

采用Tac启动子控制表达质粒，在不同的宿主细胞中表达了青霉素G酰化酶（PAC），检测这些菌株所表达的PAC活性，分析细胞内分子伴侣GroEL含量，PAC翻译后加工为α，β亚基的状况，以及它们之间的关系，结果表明：质粒pKK-SP在不同宿主中表达时，翻译后加工状况有明显差异，单位质量细胞所表达的PAC活性与翻译后加工效率相关，且与细胞内分子伴侣GroEL在菌体总蛋白中含量正相关，同时也阐明了亚基的折叠成为翻译后加工过程的限制步骤，细胞内分子伴侣GroEL有助于PAC亚基的折叠和稳定。

Effect of GroEL Chaperone on Posttranslational Process of Penicillin G Acylase Gene in E.coli

The expression level of penicillin G acylase (PAC) gene in different host strains harbouring same plasmid (pKK SP) were different, among them, the highest expression was achieved in E.coli BL21(DE3), the lowest in E.coli BL21 and moderate expression levels were observed in E.coli D816 and E.coli HB101. The special activity of penicillin G acylase gene in four host strains are all dependent on molecular chaperon GroEL content in these cells. Analysis of results from sodim dodecyl sulfate/polyacrylamide gel electrophoresis and immuno blot of whole cell proteins in these cells indicated that folding of subunits were bottleneck steps limiting posttranslational process of penicillin G acylase. The posttranslational efficiency (folding rate, secretion rate) of PAC is dependent on molecular chaperon GroEL content in these cells.