Disease relevance of flhD

• The Proteus mirabilis flagellum class I flhDC operon was isolated, and its transcript was shown to originate from a sigma70 promoter 244 bp 5' of flhD and 29 bp 3' of a putative cyclic AMP receptor protein-binding site [1].
• In the present work, the transcriptional control of the Salmonella typhimurium flhD operon was investigated in various genetic backgrounds [2].

High impact information on flhD

• Furthermore, viable flagellin-deficient mutant organisms (fliC/fljB and flhD) failed to elicit IL-8 secretion when added apically to model intestinal epithelia [3].
• QseBC activates transcription of flhDC, which is the master regulator for the flagella and motility genes and, in the absence of flhD, QseBC failed to activate the transcription of fliA [4].
• Conversely, the flhD mutant exhibited diminished invasiveness for human and mouse intestinal epithelial cells, as well as a reduced capacity to induce fluid secretion and evoke a polymorphonuclear leukocyte response in the calf ligated-loop assay [5].
• We found that the flhD mutant was more virulent than its parent in the mouse and displayed slightly faster net growth between 4 and 24 h of infection in mouse macrophages [5].
• The class 2 operons are controlled positively by the class 1 genes, flhD and flhC [6].

Biological context of flhD

• We next examined the expression of a chromosomal flhD-lac fusion gene in the presence of a plasmid carrying the wild-type flhD operon [2].

Other interactions of flhD

• In the absence of FliA or in the presence of both FliA and its cognate anti-sigma factor FlgM, the flhD operon was autogenously repressed, whereas in the flgM mutant background it was autogenously activated in the presence of FliA [2].
• More careful examination of transcription revealed that the fliA mutation reduces but does not eliminate the expression of these operons, whereas a mutation in the flhD operon, which encodes activator proteins for the class 2 operons, eliminates their expression [7].
• Mutations in the cya, crp or hns gene reduced but did not eliminate flhD expression [2].

References