Requirement for FlhA in flagella assembly and swarm-cell differentiation by Proteus mirabilis.
Swarming by Proteus mirabilis is characterized by cycles of rapid population migration across surfaces, following differentiation of typical rods into long, aseptate swarm cells that overexpress flagella and virulence factors, particularly haemolysin. A non-swarming Tn5phoA mutant was unable to synthesize flagella, to fully elongate or to induce high levels of the toxin. The mutation lay within a 2091 bp gene encoding a homologue of the Escherichia coli FlhA belonging to a family of proteins that are required for assembly of flagella or virulence proteins and that are suggested to act either directly in membrane translocation and/or in regulating synthesis of the export apparatus. In trans expression of multicopy flhA restored cell elongation and migration and generated differentiation-specific hyperexpression of flagellin and toxin genes to levels above those seen in the wild-type strain. Transcription of flhA was strongly induced during differentiation, from its own putative sigma 28 promoter. The results suggest a mechanistic coupling of flagella assembly and swarm-cell differentiation.
Gygi
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Cambridge University Department of Pathology, UK.
Bailey
M J
MJ
Allison
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Hughes
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D002465:Cell Movement / Q000235:genetics; D005408:Flagellin / Q000096:biosynthesis* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011401:Promoter Regions, Genetic; D011513:Proteus mirabilis / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D012333:RNA, Messenger / Q000032:analysis; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D001426:Bacterial Proteins; C080688:FlhA protein, Bacteria; D006460:Hemolysin Proteins; C064194:HpmA hemolysin; D008565:Membrane Proteins; D012333:RNA, Messenger; D005408:Flagellin