PMID:23028751

Citation	Wang, D, Korban, SS, Pusey, PL and Zhao, Y (2012) AmyR is a novel negative regulator of amylovoran production in Erwinia amylovora. PLoS ONE 7:e45038
Abstract	In this study, we attempted to understand the role of an orphan gene amyR in Erwinia amylovora, a functionally conserved ortholog of ybjN in Escherichia coli, which has recently been characterized. Amylovoran, a high molecular weight acidic heteropolymer exopolysaccharide, is a virulent factor of E. amylovora. As reported earlier, amylovoran production in an amyR knockout mutant was about eight-fold higher than that in the wild type (WT) strain of E. amylovora. When a multicopy plasmid containing the amyR gene was introduced into the amyR mutant or WT strains, amylovoran production was strongly inhibited. Furthermore, amylovoran production was also suppressed in various amylovoran-over-producing mutants, such as grrSA containing multicopies of the amyR gene. Consistent with amylovoran production, an inverse correlation was observed between in vitro expression of amyR and that of amylovoran biosynthetic genes. However, both the amyR knockout mutant and over-expression strains showed reduced levan production, another exopolysaccharide produced by E. amylovora. Virulence assays demonstrated that while the amyR mutant was capable of inducing slightly greater disease severity than that of the WT strain, strains over-expressing the amyR gene did not incite disease on apple shoots or leaves, and only caused reduced disease on immature pear fruits. Microarray studies revealed that amylovoran biosynthesis and related membrane protein-encoding genes were highly expressed in the amyR mutant, but down-regulated in the amyR over-expression strains in vitro. Down-regulation of amylovoran biosynthesis genes in the amyR over-expression strain partially explained why over-expression of amyR led to non-pathogenic or reduced virulence in vivo. These results suggest that AmyR plays an important role in regulating exopolysaccharide production, and thus virulence in E. amylovora.
Links	PubMed PMC3445560 Online version:10.1371/journal.pone.0045038
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Erwinia amylovora/genetics; Erwinia amylovora/metabolism; Erwinia amylovora/pathogenicity; Fructans/biosynthesis; Gene Dosage/genetics; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genes, Bacterial/genetics; Genetic Complementation Test; Malus/microbiology; Mutation/genetics; Plant Diseases/microbiology; Plant Shoots/microbiology; Polysaccharides, Bacterial/biosynthesis; Pyrus/microbiology; Virulence/genetics
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ERWAM:AMSG		GO:0015785: UDP-galactose transport	ECO:0000315:		P		Figure 1, C and D.	complete CACAO 9110
ERWAM:AMSC		GO:0006225: UDP biosynthetic process	ECO:0000315:		P		Figure 1, C and D.	complete CACAO 9111
ERWAM:AMSD		GO:0016757: transferase activity, transferring glycosyl groups	ECO:0000315:		F		Figure 1, C and D.	complete CACAO 9112
ERWAM:RCSA		GO:0009242: colanic acid biosynthetic process	ECO:0000315:		P		Figure 1, C and D.	complete CACAO 9113

References

See Help:References for how to manage references in GONUTS.