Novel genes that upregulate the Proteus mirabilis flhDC master operon controlling flagellar biogenesis and swarming
Novel genes that upregulate the Proteus mirabilis flhDC master operon controlling flagellar biogenesis and swarming
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DOI：
10.1046/j.1365-2958.1998.00967.x
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发表时间：
1998-08-01
影响因子：
3.6
通讯作者：
Hughes, C
中科院分区：
文献类型：
--
作者：
Dufour, A;Furness, RB;Hughes, C
通过筛选缺乏FlgN鞭毛组装促进剂的非集群但可移动的奇异变形杆菌突变体中的多细胞迁移恢复，我们鉴定了四个不同的基因，它们在反式和多拷贝中增加了鞭毛的产量和细胞长度，每个基因都上调了控制鞭毛生物发生、细胞分裂和聚集的flhDC主操纵子的表达，不仅在突变体中，而且在野生型中也是如此，这些基因分别被命名为umoA、umoB、umoC和umoD。每个野生型染色体UMO基因的中断都会导致群体和细胞伸长的相应减少，这与flhDC操纵子的表达减少有关。UmoA、umoB、umoC和umoD基因没有紧密连锁，只有umoB是操纵子的一部分，计算出的基因产物序列UmoA(20.6 kDa)、UmoB(78.0 kDa)、UmoC(15.2 kDa)和UmoD(19.2 kDa)含有可能的N端分泌信号，并预测了在细胞膜或周质中的位置，UmoB和UmoD分别与大肠杆菌未鉴定的开放阅读框YrfF和YcfJ有序列相似性；UmoA和UmoC没有已知的同源基因，umoD和umoC基因的转录本水平很低，但umoA和umoD的表达与flhDC相似，并且在分化为细长的超级鞭毛群细胞过程中与flhDC的表达平行增加。与flhDC、umoA和umoD一样，在缺乏FlhA出口机制内膜成分的鞭毛组装突变体中，umoA和umoD的表达受到负反馈，UMO基因表达和交叉互补的分析表明，UMO基因在上调flhDC的途径中不是顺序作用的，但揭示了flhDC相互上调，我们的发现加强了flhDC主操纵子在奇异变形杆菌和其他革兰氏阴性细菌中作为主要同化检查点的图景，并扩大了与鞭毛生物发生耦合的复杂调控网络的视野。
By screening for restoration of multicellular migration in a non-swarming but motile Proteus mirabilis mutant lacking the FlgN facilitator of flagella assembly, we identified four distinct genes that, in trans and multicopy, increased flagella production and cell length, Each of the genes upregulated expression of the flhDC master operon that controls flagellar biogenesis, cell division and swarming, not only in the mutant but also in the wild type, The genes were named umoA, umoB, umoC and umoD. Disruption of each of the wild-type chromosomal umo genes caused corresponding reductions in swarming and cell elongation, which correlated with decreased expression of the flhDC operon. The umoA, umoB, umoC and umoD genes are not closely linked, and only umoB is part of an operon, The sequences of the calculated gene products, UmoA (20.6 kDa), UmoB (78.0 kDa), UmoC (15.2 kDa) and UmoD (19.2 kDa), contain putative N-terminal secretion signals and predict a location in the cell membranes or periplasm, UmoB and UmoD have sequence similarity to the Escherichia coli uncharacterized open reading frames YrfF and YcfJ respectively; UmoA and UmoC have no known homologues, The umoD and umoC gene transcripts were present at very low levels, but umoA and umoD expression was similar to that of flhDC and increased in parallel with flhDC expression during differentiation into elongated hyperflagellated swarm cells. Like flhDC, umoA and umoD expression was subject to negative feedback in a flagellar assembly mutant lacking the FlhA inner membrane component of the export machinery, Assays of umo gene expression and cross-complementation indicated that the umo genes do not act in sequence within a pathway to upregulate flhDC, but revealed that umoA and umoD ave reciprocally upregulated by FlhDC, Our findings strengthen the picture of the flhDC master operon as a major assimilatory checkpoint in Proteus mirabilis and other Gram-negative bacteria and expand the view of a complex regulatory network coupled to flagellar biogenesis.