SaPI mutations affecting replication and transfer and enabling autonomous replication in the absence of helper phage
SaPI mutations affecting replication and transfer and enabling autonomous replication in the absence of helper phage
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DOI：
10.1111/j.1365-2958.2007.06027.x
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发表时间：
2008-02-01
影响因子：
3.6
通讯作者：
Penades, Jose R.
中科院分区：
文献类型：
--
作者：
Ubeda, Carles;Maiques, Elisa;Penades, Jose R.
SaPI是葡萄球菌和其他革兰氏阳性细菌中的染色体岛，携带超抗原、毒力因子、抗性和某些代谢功能的基因。它们与某些温和的病毒有密切的关系，涉及噬菌体诱导的切除，复制和有效包装在特殊的小头感染性噬菌体样颗粒，导致非常高的转移频率。它们通常包含18-22个ORF。我们已经系统地灭活了这些ORF中的每一个，并确定了它们的功能分组。在其他报告中，我们已经表明，五个参与切除/整合，复制和包装。在这份报告中，我们总结了突变分析，并专注于两个关键的ORF参与调控的SaPI切除复制包装周期相对于-A-维斯噬菌体诱导。这两个基因是不同的转录和定义的主要转录组织的SaPI基因组。其中之一，stl，编码主阻遏物，可能类似于标准的cI噬菌体阻遏物。该基因的突变失活导致SaPI在不存在任何诱导噬菌体的情况下切除和复制。这种复制的SaPI DNA不被包装;然而，因为衣壳组分由辅助噬菌体提供。我们还没有确定任何特定功能的第二个假定的调控基因，虽然它是高度保守的SaPI。
The SaPIs are chromosomal islands in staphylococci and other Gram-positive bacteria that carry genes for superantigens, virulence factors, resistance and certain metabolic functions. They have intimate relationships with certain temperate phages involving phage-induced excision, replication and efficient packaging in special small-headed infective phage-like particles, resulting in very high transfer frequencies. They generally contain 18-22 ORFs. We have systematically inactivated each of these ORFs and determined their functional groupings. In other reports, we have shown that five are involved in excision/integration, replication and packaging. In this report, we summarize the mutational analysis and focus on two key ORFs involved in regulation of the SaPI excision-replication-packaging cycle vis-a-vis phage induction. These two genes are divergently transcribed and define the major transcriptional organization of the SaPI genome. One of them, stl, encodes a master repressor, possibly analogous to the standard cI phage repressor. Mutational inactivation of this gene results in SaPI excision and replication in the absence of any inducing phage. This replicated SaPI DNA is not packaged; however, since the capsid components are provided by the helper phage. We have not yet ascertained any specific function for the second putative regulatory gene, though it is highly conserved among the SaPIs.