Chen S T, Clowes R C
J Bacteriol. 1987 Jul;169(7):3124-30. doi: 10.1128/jb.169.7.3124-3130.1987.
The sites of initiation for beta-lactamase mRNA transcription and the nucleotide sequences of beta-lactamase plasmids derived from Haemophilus and Neisseria species were determined. In N. gonorrhoeae, transcription from plasmid pFA3 was initiated from two sites, one located about 20 base pairs (bp) and the other 210 bp upstream of the beta-lactamase initiating codon, whereas in H. influenzae, transcriptional initiation from plasmid pHD131 occurred at two different sites, approximately 150 and 170 bp upstream of the initiating codon. When these plasmids were transformed into Escherichia coli, transcription was initiated at the 150- and 170-bp upstream sites in both plasmids. The nucleotide sequences of both plasmids within the noncoding region upstream of the transcriptional initiation site were identical and, except at two or three nucleotide positions, the sequences were also identical to the corresponding region of Tn3. At one of these positions there is a TA for CG substitution, which correlates in E. coli and Haemophilus sp. with the presence of two strong, overlapping beta-lactamase promoters, initiating transcription at the 150- and 170-bp upstream sites. Over a larger (875-bp) segment comprising most of the sequences of the tnpR and bla genes, the nucleotide sequences of both plasmids were also identical, and although this sequence differed from the corresponding Tn3 sequence at 18 sites, it was identical to that of Tn2, except at one site. The sequence of a second Haemophilus plasmid, pJB1, was identical to that of pHD131 in the same region, except at two nucleotides. All three plasmids were identical in nucleotide sequence in other TnA regions, as well as in regions flanking the TnA sequence, except that the Neisseria plasmid lacked a TnA segment of 3,298 bp [comprising the IR(L) and proximal sequences] together with approximately 273 bp of the non-TnA region adjacent to IR(L). The sequence of a second N. gonorrhoeae plasmid, pFA7, was identical to pFA3, except that the terminal, 3,299 TnA nucleotides were missing.
测定了β-内酰胺酶mRNA转录的起始位点以及源自嗜血杆菌属和奈瑟菌属的β-内酰胺酶质粒的核苷酸序列。在淋病奈瑟菌中，质粒pFA3的转录从两个位点起始，一个位于β-内酰胺酶起始密码子上游约20个碱基对（bp）处，另一个位于上游210 bp处；而在流感嗜血杆菌中，质粒pHD131的转录起始于两个不同位点，分别位于起始密码子上游约150和170 bp处。当将这些质粒转化到大肠杆菌中时，两个质粒的转录均起始于上游150和170 bp处的位点。转录起始位点上游非编码区内两个质粒的核苷酸序列相同，并且除了两三个核苷酸位置外，这些序列也与Tn3的相应区域相同。在其中一个位置存在TA到CG的替换，这在大肠杆菌和嗜血杆菌属中与两个强的、重叠的β-内酰胺酶启动子的存在相关，它们在150和170 bp上游位点起始转录。在包含tnpR和bla基因大部分序列的更大（875 bp）片段上，两个质粒的核苷酸序列也相同，尽管该序列在18个位点与相应的Tn3序列不同，但除了一个位点外，它与Tn2的序列相同。第二个流感嗜血杆菌质粒pJB1在同一区域的序列与pHD131相同，除了两个核苷酸。所有三个质粒在其他TnA区域以及TnA序列侧翼区域的核苷酸序列相同，只是奈瑟菌属质粒缺少3298 bp的TnA片段[包括IR(L)和近端序列]以及与IR(L)相邻的约273 bp非TnA区域。第二个淋病奈瑟菌质粒pFA7的序列与pFA3相同，只是缺少末端的3299个TnA核苷酸。
