Dataset Information

Antibiotic production by Erwinia herbicola Eh1087: its role in inhibition of Erwinia amylovora and partial characterization of antibiotic biosynthesis genes.

ABSTRACT: Mutants of Erwinia herbicola Eh1087 (Ant-), which did not produce antibiotic activity against Erwinia amylovora, the fire blight pathogen, were selected after TnphoA mutagenesis. In immature pear fruit Ant- mutants grew at the same rate as wild-type strain Eh1087 but did not suppress development of the disease caused by E. amylovora. These results indicated that antibiosis plays an important role in the suppression of disease by strain Eh1087. All of the Ant- mutations obtained were located in a 2.2-kb region on a 200-kb indigenous plasmid. Sequence analysis of the mutated DNA region resulted in identification of six open reading frames, designated ORF1 through ORF6, four of which were essential to antibiotic expression. One gene was identified as a gene which encodes a translocase protein which is probably involved in antibiotic secretion. A sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of plasmid proteins produced in Escherichia coli minicells confirmed the presence of proteins whose sizes corresponded to the sizes of the predicted open reading frame products.

SUBMITTER: Kearns LP

PROVIDER: S-EPMC106239 | biostudies-literature | 1998 May

REPOSITORIES: biostudies-literature

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Antibiotic production by Erwinia herbicola Eh1087: its role in inhibition of Erwinia amylovora and partial characterization of antibiotic biosynthesis genes.

Kearns L P LP Mahanty H K HK

Applied and environmental microbiology 19980501 5

Mutants of Erwinia herbicola Eh1087 (Ant-), which did not produce antibiotic activity against Erwinia amylovora, the fire blight pathogen, were selected after TnphoA mutagenesis. In immature pear fruit Ant- mutants grew at the same rate as wild-type strain Eh1087 but did not suppress development of the disease caused by E. amylovora. These results indicated that antibiosis plays an important role in the suppression of disease by strain Eh1087. All of the Ant- mutations obtained were located in a ...[more]

PMID: 9572960

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Project description:Cyclic di-GMP (c-di-GMP) is a ubiquitous bacterial second messenger molecule that is an important virulence regulator in the plant pathogen Erwinia amylovora Intracellular levels of c-di-GMP are modulated by diguanylate cyclase (DGC) enzymes that synthesize c-di-GMP and by phosphodiesterase (PDE) enzymes that degrade c-di-GMP. The regulatory role of the PDE enzymes in E. amylovora has not been determined. Using a combination of single, double, and triple deletion mutants, we determined the effects of each of the four putative PDE-encoding genes (pdeA, pdeB, pdeC, and edcA) in E. amylovora on cellular processes related to virulence. Our results indicate that pdeA and pdeC are the two phosphodiesterases most active in virulence regulation in E. amylovora Ea1189. The deletion of pdeC resulted in a measurably significant increase in the intracellular pool of c-di-GMP, and the highest intracellular concentrations of c-di-GMP were observed in the Ea1189 ?pdeAC and Ea1189 ?pdeABC mutants. The regulation of virulence traits due to the deletion of the pde genes showed two patterns. A stronger regulatory effect was observed on amylovoran production and biofilm formation, where both Ea1189 ?pdeA and Ea1189 ?pdeC mutants exhibited significant increases in these two phenotypes in vitro In contrast, the deletion of two or more pde genes was required to affect motility and virulence phenotypes. Our results indicate a functional redundancy among the pde genes in E. amylovora for certain traits and indicate that the intracellular degradation of c-di-GMP is mainly regulated by pdeA and pdeC, but they also suggest a role for pdeB in regulating motility and virulence.IMPORTANCE Precise control of the expression of virulence genes is essential for successful infection of apple hosts by the fire blight pathogen, Erwinia amylovora The presence and buildup of a signaling molecule called cyclic di-GMP enables the expression and function of some virulence determinants in E. amylovora, such as amylovoran production and biofilm formation. However, other determinants, such as those for motility and the type III secretion system, are expressed and functional when cyclic di-GMP is absent. Here, we report studies of enzymes called phosphodiesterases, which function in the degradation of cyclic di-GMP. We show the importance of these enzymes in virulence gene regulation and the ability of E. amylovora to cause plant disease.

Dataset Information

Antibiotic production by Erwinia herbicola Eh1087: its role in inhibition of Erwinia amylovora and partial characterization of antibiotic biosynthesis genes.

Publications

Antibiotic production by Erwinia herbicola Eh1087: its role in inhibition of Erwinia amylovora and partial characterization of antibiotic biosynthesis genes.

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