Bhakta Mausumi, Bal Manjusri
Department of Physiology, University of Calcutta, University Colleges of Science & Technology, 92, Acharya Prafulla Chandra Road, Kolkata-700009, India.
Curr Microbiol. 2003 Jun;46(6):413-7. doi: 10.1007/s00284-002-3841-3.
While studying antibiotic-resistant plasmids from multi-drug-resistant nosocomial Staphylococcus aureus strains, we isolated a small (2.889 kb) chloramphenicol-resistant (Cm(r)) plasmid, which was designated as pMC524/MBM. The molecular size of pMC524/MBM was close to that of pC194 (2.910 kb), a well-known Cm(r) staphylococcal plasmid. Unlike pC194, this plasmid can replicate and express itself efficiently and stably in Escherichia coli. However, Cm is needed for stable maintenance of pMC524/MBM in different hosts. In this study, the nucleotide sequences of these two plasmids were compared after sequencing of pMC524/MBM [EMBL Accession No. AJ312056 SAU312056]. Although these two plasmids have striking nucleotide sequence homology, the Plus Origin, Minus Origin, the replication protein (Rep), and the chloramphenicol acetyl transferase (Cat) have considerable variations. Possibly, these changes have modulated pMC524/MBM into an efficient shuttle-plasmid.
在研究多重耐药医院金黄色葡萄球菌菌株的抗生素抗性质粒时，我们分离出了一个小的（2.889 kb）氯霉素抗性（Cm(r)）质粒，命名为pMC524/MBM。pMC524/MBM的分子大小与著名的Cm(r)葡萄球菌质粒pC194（2.910 kb）相近。与pC194不同的是，该质粒能在大肠杆菌中高效稳定地复制和表达。然而，在不同宿主中稳定维持pMC524/MBM需要氯霉素。在本研究中，对pMC524/MBM进行测序后[EMBL登录号AJ312056 SAU312056]，比较了这两个质粒的核苷酸序列。尽管这两个质粒具有显著的核苷酸序列同源性，但正链起点、负链起点、复制蛋白（Rep）和氯霉素乙酰转移酶（Cat）存在相当大的差异。这些变化可能使pMC524/MBM转变为一种高效的穿梭质粒。
