Department of Molecular Biology and Genetics, GYTE, Gebze Institute of Technology, 41400 Kocaeli, Turkey.
World J Microbiol Biotechnol. 2012 May;28(5):2159-64. doi: 10.1007/s11274-012-1021-6. Epub 2012 Feb 14.
Penicillin G acylase (PA) is an important enzyme used in the industrial production of b-lactam antibiotics. In this study, the effects of mutations in the translation initiation region of the Escherichia coli pac gene, encoding periplasmic PA, were examined. Several mutations led to increased amounts of PA activity, including those that lengthened the spacer region between the ribosome binding site and the ATG start codon, and those with altered codons on positions +2 and +4 relative to the start codon. These results indicated that the wild-type sequence of the pac gene does not provide maximum expression levels and that the strategies applied in this study can be used to improve production of PA in E. coli. Unexpectedly, our study also suggested that translocation of PA was, in contrast to earlier reports, shown not to require the Twin-arginine translocation pathway for transport into the periplasm.
青霉素 G 酰化酶（PA）是工业生产β-内酰胺类抗生素的重要酶。在这项研究中，研究了编码周质 PA 的大肠杆菌 pac 基因翻译起始区突变的影响。一些突变导致 PA 活性增加，包括那些延长核糖体结合位点和 ATG 起始密码子之间间隔区的突变，以及那些相对于起始密码子在+2 和+4 位置改变密码子的突变。这些结果表明，pac 基因的野生型序列不能提供最大的表达水平，并且本研究中应用的策略可用于提高大肠杆菌中 PA 的产量。出乎意料的是，我们的研究还表明，与早期的报道相反，PA 的易位不需要 Twin-arginine 易位途径来运输到周质中。
