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Identification of Archaea-specific chemotaxis proteins which interact with the flagellar apparatus.

Schlesner M, Miller A, Streif S, Staudinger WF, Müller J, Scheffer B, Siedler F, Oesterhelt D - BMC Microbiol. (2009)

Bottom Line: Deletion of the second DUF439 protein had only minimal effects.Genes coding for DUF439 proteins, however, were found to be integral parts of chemotaxis gene regions across the archaeal domain, and they were not detected in other genomic context.Altogether, these results demonstrate that, in the archaeal domain, previously unrecognized archaea-specific Che proteins are essential for relaying taxis signaling to the flagellar apparatus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Membrane Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany. schlesne@biochem.mpg.de

ABSTRACT

Background: Archaea share with bacteria the ability to bias their movement towards more favorable locations, a process known as taxis. Two molecular systems drive this process: the motility apparatus and the chemotaxis signal transduction system. The first consists of the flagellum, the flagellar motor, and its switch, which allows cells to reverse the rotation of flagella. The second targets the flagellar motor switch in order to modulate the switching frequency in response to external stimuli. While the signal transduction system is conserved throughout archaea and bacteria, the archaeal flagellar apparatus is different from the bacterial one. The proteins constituting the flagellar motor and its switch in archaea have not yet been identified, and the connection between the bacterial-like chemotaxis signal transduction system and the archaeal motility apparatus is unknown.

Results: Using protein-protein interaction analysis, we have identified three proteins in Halobacterium salinarum that interact with the chemotaxis (Che) proteins CheY, CheD, and CheC2, as well as the flagella accessory (Fla) proteins FlaCE and FlaD. Two of the proteins belong to the protein family DUF439, the third is a HEAT_PBS family protein. In-frame deletion strains for all three proteins were generated and analyzed as follows: a) photophobic responses were measured by a computer-based cell tracking system b) flagellar rotational bias was determined by dark-field microscopy, and c) chemotactic behavior was analyzed by a swarm plate assay. Strains deleted for the HEAT_PBS protein or one of the DUF439 proteins proved unable to switch the direction of flagellar rotation. In these mutants, flagella rotate only clockwise, resulting in exclusively forward swimming cells that are unable to respond to tactic signals. Deletion of the second DUF439 protein had only minimal effects. HEAT_PBS proteins could be identified in the chemotaxis gene regions of all motile haloarchaea sequenced so far, but not in those of other archaeal species. Genes coding for DUF439 proteins, however, were found to be integral parts of chemotaxis gene regions across the archaeal domain, and they were not detected in other genomic context.

Conclusion: Altogether, these results demonstrate that, in the archaeal domain, previously unrecognized archaea-specific Che proteins are essential for relaying taxis signaling to the flagellar apparatus.

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Chemotaxis and motility gene cluster of H. salinarum. Genes involved in chemotaxis are shown in blue and motility genes in green. The proteins investigated in this study are shown in light blue (the homologs OE2402F and OE2404R) and cyan. A protein of unknown function is colored gray.
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Figure 1: Chemotaxis and motility gene cluster of H. salinarum. Genes involved in chemotaxis are shown in blue and motility genes in green. The proteins investigated in this study are shown in light blue (the homologs OE2402F and OE2404R) and cyan. A protein of unknown function is colored gray.

Mentions: Protein interaction analysis of the halobacterial Che proteins (Schlesner et al., unpublished; see Additional file 1 for details) revealed two proteins of unknown function, OE2402F and OE2404R, as interaction partners of CheY, CheD, and CheC2. These proteins are homologous to each other and are coded by adjacent genes, located between the che genes and the type B flagellins (Figure 1).


Identification of Archaea-specific chemotaxis proteins which interact with the flagellar apparatus.

Schlesner M, Miller A, Streif S, Staudinger WF, Müller J, Scheffer B, Siedler F, Oesterhelt D - BMC Microbiol. (2009)

Chemotaxis and motility gene cluster of H. salinarum. Genes involved in chemotaxis are shown in blue and motility genes in green. The proteins investigated in this study are shown in light blue (the homologs OE2402F and OE2404R) and cyan. A protein of unknown function is colored gray.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2666748&req=5

Figure 1: Chemotaxis and motility gene cluster of H. salinarum. Genes involved in chemotaxis are shown in blue and motility genes in green. The proteins investigated in this study are shown in light blue (the homologs OE2402F and OE2404R) and cyan. A protein of unknown function is colored gray.
Mentions: Protein interaction analysis of the halobacterial Che proteins (Schlesner et al., unpublished; see Additional file 1 for details) revealed two proteins of unknown function, OE2402F and OE2404R, as interaction partners of CheY, CheD, and CheC2. These proteins are homologous to each other and are coded by adjacent genes, located between the che genes and the type B flagellins (Figure 1).

Bottom Line: Deletion of the second DUF439 protein had only minimal effects.Genes coding for DUF439 proteins, however, were found to be integral parts of chemotaxis gene regions across the archaeal domain, and they were not detected in other genomic context.Altogether, these results demonstrate that, in the archaeal domain, previously unrecognized archaea-specific Che proteins are essential for relaying taxis signaling to the flagellar apparatus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Membrane Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany. schlesne@biochem.mpg.de

ABSTRACT

Background: Archaea share with bacteria the ability to bias their movement towards more favorable locations, a process known as taxis. Two molecular systems drive this process: the motility apparatus and the chemotaxis signal transduction system. The first consists of the flagellum, the flagellar motor, and its switch, which allows cells to reverse the rotation of flagella. The second targets the flagellar motor switch in order to modulate the switching frequency in response to external stimuli. While the signal transduction system is conserved throughout archaea and bacteria, the archaeal flagellar apparatus is different from the bacterial one. The proteins constituting the flagellar motor and its switch in archaea have not yet been identified, and the connection between the bacterial-like chemotaxis signal transduction system and the archaeal motility apparatus is unknown.

Results: Using protein-protein interaction analysis, we have identified three proteins in Halobacterium salinarum that interact with the chemotaxis (Che) proteins CheY, CheD, and CheC2, as well as the flagella accessory (Fla) proteins FlaCE and FlaD. Two of the proteins belong to the protein family DUF439, the third is a HEAT_PBS family protein. In-frame deletion strains for all three proteins were generated and analyzed as follows: a) photophobic responses were measured by a computer-based cell tracking system b) flagellar rotational bias was determined by dark-field microscopy, and c) chemotactic behavior was analyzed by a swarm plate assay. Strains deleted for the HEAT_PBS protein or one of the DUF439 proteins proved unable to switch the direction of flagellar rotation. In these mutants, flagella rotate only clockwise, resulting in exclusively forward swimming cells that are unable to respond to tactic signals. Deletion of the second DUF439 protein had only minimal effects. HEAT_PBS proteins could be identified in the chemotaxis gene regions of all motile haloarchaea sequenced so far, but not in those of other archaeal species. Genes coding for DUF439 proteins, however, were found to be integral parts of chemotaxis gene regions across the archaeal domain, and they were not detected in other genomic context.

Conclusion: Altogether, these results demonstrate that, in the archaeal domain, previously unrecognized archaea-specific Che proteins are essential for relaying taxis signaling to the flagellar apparatus.

Show MeSH
Related in: MedlinePlus