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- Wright, Sandra A. I., et al.
(författare)
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Genes for biosynthesis of pantocin A and B by Pantoea agglomerans Eh318
- 2002
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Ingår i: Proceedings of the 9th international workshop on fire blight. - 9066058064 ; , s. 237-241
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Konferensbidrag (refereegranskat)abstract
- Pantoea agglomerans strain Eh318 has been effective in biological control tests against fire blight and it inhibits the growth of Erwinia amylovora on minimal media. A double zone of inhibition on a plate containing a soft-agar overlay seeded with E. amylovora suggests the action of two distinct antibiotics, pantocin A and pantocin B. The structural characterization of pantocin A is underway, whereas that of pantocin B has been determined to be (R)-N-[((S)-2-Amino-propanoylamino)methyl]-2-methanesulfonyl-succinami c acid. Subcloning and transposon mutagenesis data suggested that the genetic region involved in the biosynthesis of pantocin A is 2.7 kb at most, while that of pantocin B is at least 18.5 kb. The open reading frames (ORF) found within the pantocin A biosynthetic region were designated paaA, paaB and paaC There is also a small ORF present upstream of the paaABC operon. The genes of the operon are similar in organization and, in the case of paaA, in DNA sequence to those involved in microcin C7 biosynthesis in Escherichia coli. Sequencing of the 18.5 kb biosynthetic region for pantocin B has commenced. Results thus far indicate that the region contains genes with putative amino acid sequence similarity to enzymes involved in the biosynthesis of and resistance to other antibiotics. Marker-exchange mutants of Eh318 deficient in the production of pantocin A (Eh421; PanA-), pantocin B (Eh439; PanB-) or both antibiotics (Eh440; PanAB-) were created. Strain Eh440 (PanAB-) was only marginally less effective than Eh318 in several immature pear fruit tests.
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- Wright, Sandra A. I., et al.
(författare)
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Pantoea agglomerans strain EH318 produces two antibiotics that inhibit Erwinia amylovora in vitro
- 2001
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 67:1, s. 284-292
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Tidskriftsartikel (refereegranskat)abstract
- Pantoea agglomerans (synonym: Erwinia herbicola) strain Eh318 produces through antibiosis a complex zone of inhibited growth in an overlay seeded with Erwinia amylovora, the causal agent of fire blight, This zone is caused by two antibiotics, named pantocin A and B. Using a genomic library of Eh318, two cosmids, pCPP702 and pCPP704, were identified that conferred on Escherichia coli the ability to inhibit growth of E. amylovora. The two cosmids conferred different antibiotic activities on E. coil DH5 alpha. and had distinct restriction enzyme profiles. A smaller, antibiotic-conferring DNA segment from each cosmid was cloned, Each subclone was characterized and mutagenized with transposons to generate clones that were deficient in conferring pantocin A and B production, respectively. Mutated subclones were introduced into Eh318 to create three antibiotic-detective marker exchange mutants: strain Eh421 (pantocin A deficient); strain Eh439 (pantocin B deficient), and Eh440 (deficient in both pantocins), Cross-hybridization results, restriction maps, and spectrum-of-activity data using the subclones and marker exchange mutants, supported the presence of two distinct antibiotics, pantocin A and pantocin B, whose biosynthetic genes were present in pCPP702 and pCPP704, respectively. The structure of pantocin A is unknown, whereas that of pantocin B has been determined as (R)-N-[((S)-2-amino-propanoylamino)-methyl]-2-methanesulfonyl-succinam ic acid. The two pantocins mainly affect other enteric bacteria, based on limited testing.
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