Actinobacillus actinomycetemcomitans harbours type IV secretion system genes on a plasmid and in the chromosome.
Actinobacillus actinomycetemcomitans harbours type IV secretion system genes on a plasmid and in the chromosome.
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Actinobacillus actinomycetemcomitans 在质粒和染色体上携带 IV 型分泌系统基因。
DOI：
10.1099/00221287-147-11-3027
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Pelaez,M
中科院分区：
文献类型：
--
作者：
Novak,KF;Dougherty,B;Pelaez,M
Nine contiguous genes encoding a potential type IV secretion system have been identified in the chromosome ofActinobacillus actinomycetemcomitansstrain VT747 and on a plasmid (pVT745) in strain VT745. Seven of these genes encode predicted proteins that share significant homology with type IV secretion proteins inBordetella pertussis(ptloperon),Brucella melitensisbiovarsuisandAgrobacterium tumefaciens(virBoperons), where they are involved in protein secretion, pathogen intracellular survival and multiplication, and DNA transport, respectively. Results of previous studies have demonstrated that pVT745 is a conjugative plasmid and that a secondary plasmid, pMMB67, can be mobilized from strain VT745. Given these results, it was hypothesized that (1) the type IV secretion genes on pVT745 are responsible for these two functions and (2) the type IV VT747 chromosomal genes also play a role in the transport of DNA. Wild-type and mutant strains of VT745 were evaluated for their conjugative abilities. Wild-type mating efficiency was 10−6transconjugants per donor, while the mutant strain yielded no transconjugants. Wild-type VT745 harbouring a co-resident plasmid, pMMB67, mobilized pMMB67 at a frequency of 10−6, while VT747 was unable to mobilize this plasmid. These results support the hypothesis that the plasmid-encoded type IV secretion system on pVT745 is involved in DNA transport. However, the chromosomally encoded secretion system may not play a role in DNA transport in strain VT747. While the precise function of these chromosomal genes in strain VT747 has not been determined, Northern blot analyses demonstrated that these genes are expressed in bothAct. actinomycetemcomitansstrains VT745 and VT747.
