PMID:23103488

Citation	Xu, J, Kim, J, Danhorn, T, Merritt, PM and Fuqua, C Phosphorus limitation increases attachment in Agrobacterium tumefaciens and reveals a conditional functional redundancy in adhesin biosynthesis. Res. Microbiol. 163:674-84
Abstract	Bacterial responses to phosphorus limitation, commonly inorganic phosphate (P(i)), are important survival mechanisms in a variety of environments. The two-component sensor kinase PhoR and its cognate response regulator PhoB are central to the P(i) limitation response of many bacteria and control the large Pho regulon. Limitation for P(i) significantly increased attachment and biofilm formation by the plant pathogen Agrobacterium tumefaciens, and this was driven by PhoB. Surprisingly, it was also found that both phoR and phoB were essential in A. tumefaciens. Expression of a plasmid-borne copy of the low affinity P(i) transporter (pit) from Sinorhizobium meliloti in A. tumefaciens abolished the phoB and phoR essentiality in A. tumefaciens and allowed direct demonstration of the requirement for this regulatory system in the biofilm response. Increased attachment under P(i) limitation required a unipolar polysaccharide (UPP) adhesin. Mutation of a polyisoprenylphosphate hexose-1-phosphate transferase (PHPT) called uppE abolished UPP production and prevented surface attachment under P(i)-replete conditions, but this was rescued under P(i) limitation, and this rescue required phoB. In low P(i) conditions, either uppE or a paralogous gene Atu0102 is functionally redundant, but only uppE functions in UPP synthesis and attachment when P(i) is replete. This conditional functional redundancy illustrates the influence of phosphorus availability on A. tumefaciens surface colonization.
Links	PubMed Online version:10.1016/j.resmic.2012.10.013
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AGRT5:A9CKA3		GO:0042710: biofilm formation	ECO:0000315:		P		In the presence of low levels of phosphate, the biofilms are abundant, whereas in higher concentrations of phosphate, the rate of biofilms is low, as seen in figure 2	complete
AGRT5:Q7D1H9		GO:0000155: phosphorelay sensor kinase activity	ECO:0000314:		F		Fig 1. supports the function of Two component sensor kinase.	complete
AGRT5:Q7CZP5		GO:0042710: biofilm formation	ECO:0000315:		P		Figure 1 shows phoB has a role as a biofilm formation simulator based on the mutant phenotype.	complete

References

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