PMID:17581122

Citation	Inclán, YF, Vlamakis, HC and Zusman, DR (2007) FrzZ, a dual CheY-like response regulator, functions as an output for the Frz chemosensory pathway of Myxococcus xanthus. Mol. Microbiol. 65:90-102
Abstract	Myxococcus xanthus utilizes two distinct motility systems for movement (gliding) on solid surfaces: adventurous motility (A-motility) and social motility (S-motility). Both systems are regulated by the Frz signal transduction pathway, which controls cell reversals required for directed motility and fruiting body formation. The Frz chemosensory system, unlike the Escherichia coli chemotaxis system, contains proteins with multiple response regulator domains: FrzE, a CheA-CheY hybrid protein, and FrzZ, a CheY-CheY hybrid protein. Previously, the CheY domain of FrzE was hypothesized to act as the response regulator output of the Frz system. In this study, using a genetic suppressor screen, we identified FrzZ and showed FrzZ is epistatic to FrzE, demonstrating that FrzZ is the principal output component of the pathway. We constructed M. xanthus point mutations in the phosphoaccepting aspartate residues of FrzZ and demonstrated the respective roles of these residues in group and single cell motility. We also performed in vitro assays and showed rapid phosphotransfer between the CheA domain of FrzE and each of the CheY domains of FrzZ. These experiments showed that FrzZ plays a direct role as an output of the Frz chemosensory pathway and that both CheY domains of FrzZ are functional.
Links	PubMed Online version:10.1111/j.1365-2958.2007.05774.x
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Gene Expression Regulation, Bacterial; Membrane Proteins; Myxococcus xanthus/genetics; Myxococcus xanthus/growth & development; Myxococcus xanthus/metabolism; Myxococcus xanthus/physiology; Point Mutation; Recombinant Fusion Proteins/genetics; Recombinant Fusion Proteins/metabolism; Signal Transduction
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
MYXXA:Q7BU54	involved_in	GO:0071976: cell gliding	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
MYXXA:Q7BU54	enables	GO:0000156: phosphorelay response regulator activity	ECO:0000315: mutant phenotype evidence used in manual assertion		F		Seeded From UniProt	complete
MYXXA:Q7BU54		GO:0000156: phosphorelay response regulator activity	ECO:0000315:		F		Fig 4B shows that radiolabelled phosphate is transferred from FrzE when in the presence of FrzZ as seen by the appearnace of a radiolabelled band in lane 3 at the FrzZ position. Fig 4B also shows that both domains of FrzZ are able to be phosphorylated by FrzE through the individual mutation of each domain at an aspartate residue, as seen by a decrease in band intensity at the FrzECheA position and the appearance of a radiolabbelled band at the FrzZ position in lanes 4 & 5. Phosphotransfer can not occur when both domains are mutated concurrently at an aspartate residue as evidenced from a lack of a radiolabelled band at the FrzZ position in lane 6.	complete CACAO 7058
MYXXA:Q7BU54		GO:0071976: cell gliding	ECO:0000315:		P		Fig. 3 shows that the strain with mutations in both phosphorylation sites in frzZ exhibits the same phenotype as strains that have a complete deletion of frzZ. As seen in Fig 3B, these two strains have inhibited motility, in comparison to the wild-type strain, as evident by a smaller colony diameter on both 0.3% agar and 1.5% agar. Further, strains with a mutation in one of the possible phosphorylation sites exhibited motility similar to wild-type indicating that phosphorylation can occur at one site or the other as well as the role of frzZ in cell motility.	complete CACAO 7188

References

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