Role of Xer site-specific recombination in the genesis of pJHCMW1: an evolutionary hypothesis.
Role of Xer site-specific recombination in the genesis of pJHCMW1: an evolutionary hypothesis.
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Xer 位点特异性重组在 pJHCMW1 发生中的作用：进化假设。
DOI：
10.1016/j.jgar.2023.07.017
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发表时间：
2023
影响因子：
4.6
通讯作者：
Tolmasky,MarceloE
中科院分区：
文献类型：
--
作者：
Traglia,German;Ramirez,MariaSoledad;Tolmasky,MarceloE
克雷伯氏肺炎杆菌是一种革兰氏阴性杆菌，是社区获得性和医院感染的已知原因[1]。感染的表现非常多样，包括肺炎、尿路、软组织和血流感染、败血症和脑膜炎。K.肺炎也可能导致原发性肝脓肿，这是某些地区糖尿病患者的并发症，也可能导致自身免疫性疾病强直性脊柱炎，这是既往感染的后遗症[1，2]。近年来，由于获得了遗传决定簇（其中几种是质粒介导的），这种细菌引起的死亡率显著增加，这些遗传决定簇指定了多种抗生素耐药性和毒力因子[1，2]。K.已知肺炎菌株含有几种质粒[2]。pJHCMW 1质粒分离自致死性新生儿感染病原体的临床菌株[3]。对该质粒进行了深入研究和详细表征。它通过RNA调节机制复制，每个细胞的拷贝数为24 ± 7。它的回转直径为265 nm，主要位于细胞的两极，能够沿着细胞的长轴在两极之间移动[4]。pJHCMW 1质粒由一个3361-bp片段和7993-bp转座子Tn1331组成，该片段含有遗传功能，即复制、稳定性和接合。图1A显示了pJHCMW 1的详细遗传图谱[3]。搜索可能是pJHCMW 1前体的质粒，得到了pLAO 95的完整核苷酸序列，pLAO 95是一种2，857-bp的隐蔽大肠杆菌质粒[5]。其核苷酸序列与pJHCMW 1 DNA的同源性为99%。pJHCMW 1（mwr）和pLAO 95（mwr *）的Xer位点特异性重组位点在中心区域的一个核苷酸上不同（图1B）。然而，pJHCMW 1包含一个短片段，该片段包含部分XerC结合位点、mwr * 中心区和XerD结合位点，这些位点与mwr一起位于pJHCMW 1特异性DNA片段（图1B中的黑色）的侧翼，该DNA片段可能是通过Xer位点特异性重组获得的。pLAO 95进化机制的假说导致了
Klebsiella pneumoniae, a gram-negative rod, is a known cause of community-acquired and nosocomial infections [1]. The manifestations of infections are very diverse, including pneumonia, urinary tract, soft tissue and bloodstream infection, sepsis, and meningitis. K. pneumoniae can also be responsible for primary liver abscess, a complication in diabetic patients in some geographical regions, and for the autoimmune disease ankylosing spondylitis as a sequela of a previous infection [1, 2]. The mortality caused by this bacterium have significantly increased in recent years as a consequence of the acquisition of genetic determinants, several of them plasmid-mediated, that specify multiple antibiotic resistance and virulence factors [1, 2]. K. pneumoniae strains are known to harbor several plasmids [2]. The pJHCMW1 plasmid was isolated from a clinical strain that was the causative agent of a fatal newborn infection [3]. This plasmid was intensely studied and characterized in detail. It replicates through an RNA-regulated mechanism and has a copy number of 24±7 per cell. It has a diameter of gyration of 265 nm, and it is mainly located at the poles of the cell with the capacity to move between the poles along the cell’s long axis [4]. The pJHCMW1 plasmid is composed of a 3361-bp fragment that contains the inheritance functions, ie, replication, stability, and conjugation, and the 7993-bp transposon Tn1331. Figure 1A shows a detailed genetic map of pJHCMW1 [3].A search for a plasmid that could be a precursor of pJHCMW1 yielded the complete nucleotide sequence of pLAO95, a cryptic Escherichia coli plasmid of 2,857-bp [5]. An analysis of its nucleotide sequence showed 99% identity with pJHCMW1 DNA. The Xer site-specific recombination sites of pJHCMW1 (mwr) and pLAO95 (mwr*) differ in one nucleotide at the central region (Fig. 1B). However, pJHCMW1 includes a short fragment encompassing part of the XerC-binding site, the mwr* central region, and the XerD-binding site that together with mwr flank a DNA fragment particular to pJHCMW1 (black in Fig. 1B) that could have been acquired with the participation of Xer site-specific recombination. The hypothesis for the pLAO95 evolutionary mechanism that led to