Characterization of a Vibrio vulnificus LysR homologue, HupR, which regulates expression of the haem uptake outer membrane protein, HupA

被引:31
作者
Litwin, CM [1 ]
Quackenbush, J [1 ]
机构
[1] Univ Utah, Dept Pathol, Sect Clin Immunol Microbiol & Virol, Salt Lake City, UT 84132 USA
关键词
Vibrio vulnificus; haem receptor; LysR; Fur; iron; HupR;
D O I
10.1006/mpat.2001.0472
中图分类号
R392 [医学免疫学]; Q939.91 [免疫学];
学科分类号
100102 ;
摘要
In Vibrio vulnificus, the ability to acquire iron from the host has been shown to correlate with virulence. Here, we show that the DNA upstream of hupA (haem uptake receptor) in V vulnificus encodes a protein in the inverse orientation to hupA (named hupR). HupR shares homology with the LysR family of positive transcriptional activators. A hupA-lacZ fusion contained on a plasmid was transformed into Fur(-), Fur(+) and HupR(-) strains of V vulnificus. The beta-galactosidase assays and Northern blot analysis showed that transcription of hupA is negatively regulated by iron and the Fur repressor in V vulnificus. Under low-iron conditions with added haemin, the expression of hupA in the hupR mutant was significantly lower than in the wild-type. This diminished response to haem was detected by both Northern blot and hupA-lacZ fusion analysis. The haem response of hupA in the hupR mutant was restored to wild-type levels when complemented with hupR in trans. These studies suggest that HupR may act as a positive regulator of hupA transcription under low-iron conditions in the presence of haemin. (C) 2001 Academic Press.
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页码:295 / 307
页数:13
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