Point mutations in HpuB enable gonococcal HpuA deletion mutants to grow on hemoglobin.
نویسندگان
چکیده
Neisseria gonorrhoeae ordinarily requires both HpuA and HpuB to use hemoglobin (Hb) as a source of iron for growth. Deletion of HpuA resulted in reduced Hb binding and failure of growth on Hb. We identified rare Hb-utilizing colonies (Hb(+)) from an hpuA deletion mutant of FA1090, which fell into two phenotypic classes. One class of the Hb(+) revertants required expression of both TonB and HpuB for growth on Hb, while the other class required neither TonB nor HpuB. All TonB/HpuB-dependent mutants had single amino acid alterations in HpuB, which occurred in clusters, particularly near the C terminus. The point mutations in HpuB did not restore normal Hb binding. Human serum albumin inhibited Hb-dependent growth of HpuB point mutants lacking HpuA but did not inhibit growth when expression of HpuA was restored. Thus, HpuB point mutants internalized heme in the absence of HpuA despite reduced binding of Hb. HpuA facilitated Hb binding and was important in allowing use of heme from Hb for growth.
منابع مشابه
Identification and purification of a hemoglobin-binding outer membrane protein from Neisseria gonorrhoeae.
The majority of in vitro-grown Neisseria gonorrhoeae strains were unable to use hemoglobin as the sole source of iron for growth (Hgb-), but a minor population was able to do so (Hgb+). The ability of Hgb+ gonococci to utilize hemoglobin as the iron source was associated with the expression of an iron-repressible 89-kDa hemoglobin-binding protein in the outer membrane. The N-terminal amino acid...
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ورودعنوان ژورنال:
- Journal of bacteriology
دوره 184 2 شماره
صفحات -
تاریخ انتشار 2002