title: The Master Regulators of the Fla1 and Fla2 Flagella of Rhodobacter sphaeroides Control the Expression of Their Cognate CheY Proteins.
abstract: Rhodobacter sphaeroidesis an alphaproteobacterium that has two complete sets of flagellar genes. Thefla1set was acquired by horizontal transfer from an ancestral gammaproteobacterium and is the only set of flagellar genes that is expressed during growth under standard laboratory conditions. The products of these genes assemble a single, subpolar flagellum. In the absence of the Fla1 flagellum, a gain-of-function mutation in the histidine kinase CckA turns on the expression of thefla2flagellar genes through the response regulator CtrA. The rotation of the Fla1 and Fla2 flagella is controlled by different sets of chemotaxis proteins. Here, we show that the expression of the chemotaxis proteins that control Fla2, along with the expression of thefla2genes, is coordinated by CtrA, whereas the expression of the chemotaxis genes that control Fla1 is mediated by the master regulators of the Fla1 system. The coordinated expression of the chemosensory proteins with their cognate flagellar genes highlights the relevance of integrating the expression of the horizontally acquiredfla1genes with a chemosensory system independently of the regulatory proteins responsible for the expression offla2and its cognate chemosensory system.IMPORTANCEGene acquisition via horizontal transfer represents a challenge to the recipient organism to adjust its metabolic and genetic networks to incorporate the new material in a way that represents an adaptive advantage. In the case ofRhodobacter sphaeroides, a complete set of flagellar genes was acquired and successfully coordinated with the native flagellar system. Here we show that the expression of the chemosensory proteins that control flagellar rotation is dependent on the master regulators of their corresponding flagellar system, minimizing the use of transcription factors required to express the native and horizontally acquired genes along with their chemotaxis proteins.
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: José
authors.initials: J
authors.lastname: Hernandez-Valle
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Clelia
authors.initials: C
authors.lastname: Domenzain
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: de la Mora
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Poggio
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Georges
authors.initials: G
authors.lastname: Dreyfus
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico rosal@servidor.unam.mx.
authors.forename: Laura
authors.initials: L
authors.lastname: Camarena
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002633:Chemotaxis / Q000235:genetics / Q000502:physiology*; D005407:Flagella / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D000071677:Histidine Kinase / Q000235:genetics / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D000071677:Histidine Kinase
keywords: CtrA; FleQ; Rhodobacter sphaeroides; RpoN; bacterial flagellum; chemotaxis; horizontal transfer; sigma-54