PUL ID

PUL0412

PubMed

12795379, Mol Plant Microbe Interact. 2003 Jun;16(6):536-44. doi: 10.1094/MPMI.2003.16.6.536.

Characterization method

clone and expression, enzyme activity assay

Genomic accession number

AF417111

Nucelotide position range

170-3605

Substrate

polygalacturonic acid

Loci

pheC-euxT

Species

Ralstonia solanacearum/305

Degradation or Biosynthesis

degradation

Gene Name

Locus Tag

Protein ID

Gene Position

GenBank Contig Range

EC Number

pehC - AAL24033.1 169 - 2209 (+) AF417111.1:339-2379 -
exuT - AAL24034.1 2284 - 3605 (+) AF417111.1:2454-3775 -

Cluster number

1

Gene name

Gene position

Gene type

Found by CGCFinder?

- 170 - 2209 (+) CAZyme: GH28 Yes
- 2286 - 3605 (+) TC: gnl|TC-DB|P0AA78|2.A.1.14.2 Yes

PUL ID

PUL0412

PubMed

12795379, Mol Plant Microbe Interact. 2003 Jun;16(6):536-44. doi: 10.1094/MPMI.2003.16.6.536.

Title

Characterization of a Ralstonia solanacearum operon required for polygalacturonate degradation and uptake of galacturonic acid.

Author

Gonzalez ET, Allen C

Abstract

The bacterial wilt pathogen Ralstonia solanacearum produces three extracellular polygalacturonases (PGs): PehA, PehB, and PehC. All three PGs hydrolyze pectin's polygalacturonic acid backbone, but each releases different reaction products. PehA and PehB contribute significantly to pathogen virulence, probably by facilitating root invasion and colonization. To determine the collective contribution of PGs to virulence and saprophytic survival, we cloned, characterized, and mutated the R. solanacearum pehC gene, which encodes a distinctive monogalacturonate-releasing exo-PG. The virulence of a pehC mutant on tomato was indistinguishable from that of its wild-type parent; thus, this exo-PG alone does not contribute significantly to wilt pathogenesis. Unexpectedly, a completely PG-deficient triple pehA/B/C mutant was slightly more virulent than a pehA/B mutant. PehC may degrade galacturonide elicitors of host defense, thereby protecting the pathogen from plant antimicrobial responses. A galacturonate transporter gene, exuT, is immediately downstream of pehC and the two genes are co-transcribed. It has been hypothesized that galacturonic acid released by PGs from plant cell walls nourishes bacteria during pathogenesis. To separate the pectolytic and nutrient-generating roles of the PGs, we made an exuT mutant, which still produces all three isozymes of PG but cannot uptake PG degradation products. This exuT mutant had wild-type virulence on tomato, demonstrating that metabolism of galacturonic acid does not contribute significantly to bacterial success inside the plant.