A Francisella tularensis pathogenicity island required for intramacrophage growth
A Francisella tularensis pathogenicity island required for intramacrophage growth
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DOI：
10.1128/jb.186.19.6430-6436.2004
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发表时间：
2004-10-01
影响因子：
3.2
通讯作者：
Elkins, KL
中科院分区：
文献类型：
--
作者：
Nano, FE;Zhang, N;Elkins, KL
土拉热弗朗西丝菌是一种革兰氏阴性、兼性胞内病原体，可引起高度传染性的人畜共患土拉菌病。我们发现了一个病例。30 kb毒力岛。土拉热菌（FPI），其包括4个2.5至3.9 kb的大开放阅读框（ORF）和13个1.5 kb或更小的ORF。以前，位于FPI中心附近的两个小基因被证明是巨噬细胞内生长所必需的。在这项工作中，我们表明，两个大的ORF，位于FPI的两端，需要的毒力。尽管FPI中的大多数基因编码的蛋白质的氨基酸序列在高毒力和低毒力菌株之间高度保守，但其中一个FPI基因存在于高毒力AF型中。土拉热菌，在中等毒性B F型中不存在。tularensis，F.土拉热亚种novicida，其对小鼠具有高毒性，但对人类无毒。FPI的17.7-kb片段的G+C含量为26.6%，比F的平均G+C含量低6.6%。土拉热菌基因组。这种极低的G+C含量表明，DNA是从一种含有极低G+ C的染色体的微生物中输入的。
Francisella tularensis is a gram-negative, facultative intracellular pathogen that causes the highly infectious zoonotic disease tularemia. We have discovered a ca. 30-kb pathogenicity island of F. tularensis (FPI) that includes four large open reading frames (ORFs) of 2.5 to 3.9 kb and 13 ORFs of 1.5 kb or smaller. Previously, two small genes located near the center of the FPI were shown to be needed for intramacrophage growth. In this work we show that two of the large ORFs, located toward the ends of the FPI, are needed for virulence. Although most genes in the FPI encode proteins with amino acid sequences that are highly conserved between high- and low-virulence strains, one of the FPI genes is present in highly virulent type A F. tularensis, absent in moderately virulent type B F. tularensis, and altered in F. tularensis subsp. novicida, which is highly virulent for mice but avirulent for humans. The G+C content of a 17.7-kb stretch of the FPI is 26.6%, which is 6.6% below the average G+C content of the F. tularensis genome. This extremely low G+C content suggests that the DNA was imported from a microbe with a very low G+C-containing chromosome.