Phase variation of HpuAB and HmbR, two distinct haemoglobin receptors of Neisseria meningitidis DNM2
Phase variation of HpuAB and HmbR, two distinct haemoglobin receptors of Neisseria meningitidis DNM2
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DOI：
10.1046/j.1365-2958.1999.01409.x
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发表时间：
1999-06-01
影响因子：
3.6
通讯作者：
Dyer, DW
中科院分区：
文献类型：
--
作者：
Lewis, LA;Gipson, M;Dyer, DW
我们之前已经描述了HpuAB，它是一种双组分受体，介导与血红蛋白(Hb)、血红蛋白-结合珠蛋白(HB-HP)和脱脂结合珠蛋白(Hp)的结合。在这次交流中，我们构建了hpuA和hpuB基因座的非极性突变，以检测HpuA和HpuB的单独作用。我们的结果表明，HpuA和HpuB都是从Hb和Hb-HP中获取铁所必需的。我们以10(-3)的频率分离了我们的Hb利用阴性(HB-)HPU突变体的Hb利用阳性(HBF)变体，并证明Hb+表型是第二个Hb受体HmbR表达的结果。研究发现，HmbR在DNM2中的表达受位于hmbR基因座上的聚鸟嘌呤(G)链的翻译移码控制。HpuA基因还含有一条Poly(G)链，这表明脑膜炎球菌可以通过在hpuA和hmbR中发现的Poly(G)链的滑链错配来独立地改变每个HB受体的时相。因此，我们分离到了DNM2的一个自然存在的HB-变体，命名为DNM2 HB-，它既不表达HpuAB，也不表达HmbR。选择DNM2Hb-的Hb+变异体，检测HpuAB和HmbR的表达。在每种情况下，HpuAB或HmbR表达的获得都与每个Hb受体的聚(G)束的时相变化相关。
We have previously described HpuAB, a two-component receptor that mediates binding to haemoglobin (Hb), haemoglobin-haptoglobin (Hb-Hp) and apo-haptoglobin (Hp). In this communication, we constructed non-polar mutations in the hpuA and hpuB loci to examine the individual roles of HpuA and HpuB. Our results indicate that both HpuA and HpuB are required for the acquisition of Fe from Hb and Hb-Hp. We isolated Hb utilization-positive (Hbf) variants of our Hb utilization-negative (Hb-) hpu mutants at a frequency of 10(-3) and demonstrated that the Hb+ phenotype resulted from the expression of a second Hb receptor, HmbR. Expression of HmbR in DNM2 was found to be controlled by translational frameshifting involving a polyguanine (G) tract located within the hmbR locus. The hpuA locus also contains a poly(G) tract, which suggested that meningococci could phase vary each Hb receptor independently by slip-strand mispairing in the poly(G) tracts found in hpuA and hmbR. Thus, we isolated a naturally occurring Hb- variant of DNM2, designated DNM2 Hb-, which did not express either HpuAB or HmbR. Hb+ variants of DNM2Hb- were selected and examined for HpuAB and HmbR expression. In each instance, acquisition of HpuAB or HmbR expression was correlated with phase variation in the poly(G) tract of each Hb receptor.