Negative feedback from a Proteus class II flagellum export defect to the flhDC master operon controlling cell division and flagellum assembly
Negative feedback from a Proteus class II flagellum export defect to the flhDC master operon controlling cell division and flagellum assembly
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DOI：
10.1128/jb.179.17.5585-5588.1997
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发表时间：
1997-09-01
影响因子：
3.2
通讯作者：
Hughes, C
中科院分区：
文献类型：
--
作者：
Furness, RB;Fraser, GM;Hughes, C
奇异变形杆菌鞭毛I类flhDC操纵子被分离，并且其转录物被证明源自σ（70）启动子fIhD的244 bp 5'和推定的环AMP受体蛋白结合位点的29 bp 3'。随着细胞分化成细长的超鞭毛群丝，这种调节性主操纵子的表达强烈增加，并且人工过表达flhDC的细胞群迁移得更快更快。II类flhA转座子突变体在鞭毛III类基因表达中降低，如从鼠伤寒沙门氏菌中证实的FlgM抗σ（28）积累所预期的，但在细胞伸长中也出乎意料地降低。我们表明，flhDC转录物的水平在该鞭毛输出突变体中低约10倍，表明在鞭毛组装缺陷的细胞中，存在经由flhDC的附加负反馈。为了支持这一观点，在flhA突变体中人工过表达flhDC恢复了伸长，但没有恢复III类鞭毛基因的转录。
The Proteus mirabilis flagellum class I flhDC operon was isolated, and its transcript was shown to originate from a sigma(70) promoter 244 bp 5' of fIhD and 29 bp 3' of a putative cyclic AMP receptor protein-binding site. Expression of this regulatory master operon increased strongly as cells differentiated into elongated hyper-flagellated swarm filaments, and cell populations artificially overexpressing flhDC migrated sooner and faster. A class II flhA transposon mutant was reduced in flagellum class III gene expression, as would be expected from the FlgM anti-sigma(28) accumulation demonstrated in Salmonella typhimurium, but was unexpectedly also reduced in cell elongation, Were, we show that levels of flhDC transcript were ca 10-fold lower in this flagellum export mutant, indicating that in cells defective in flagellum assembly, there is additional negative feedback via flhDC. In support of this view, artificial overexpression of flhDC in the flhA mutant restored elongation but not class III flagellum gene transcription.