The c-di-GMP phosphodiesterase VmpA absent in Escherichia coli K12 strains affects motility and biofilm formation in the enterohemorrhagic O157:H7 serotype.
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a foodborne pathogen that resists the acidic gastric environment, colonizes the gut epithelium, and causes hemorrhagic colitis and hemolytic-uremic syndrome, especially in children. The genomic island OI-47 of E. coli O157:H7 contains a gene, z1528, encoding an EAL-domain protein potentially involved in c-di-GMP hydrolysis that is absent in non-pathogenic E. coli. This gene, designated vmpA, is co-transcribed with ycdT, which is present in non pathogenic E. coli and encodes a diguanylate cyclase involved in c-di-GMP synthesis. To test for vmpA function, we constructed a vmpA knockout mutant. We also overexpressed vmpA, purified the VmpA protein and assayed for its activity in vitro. We found that VmpA possesses c-di-GMP phosphodiesterase activity and that the vmpA mutation results in increased biofilm formation, and reduced swimming motility, which is consistent with the function determined in vitro. Unexpectedly, suppressor mutations arise frequently in the vmpA background suggesting that VmpA plays an important regulatory role in E. coli O157:H7. These findings represent an example of remarkable flexibility in the organization of c-di-GMP signaling pathways in closely related species.
INRA, Institut National de la Recherche Agronomique, UR454 Unité de Microbiologie, Centre de Recherche de Clermont-Ferrand-Theix, 63122 Saint-Genès-Champanelle, France.
Priscilla
P
Branchu
Thomas
T
Hindré
Xin
X
Fang
Robynn
R
Thomas
Mark
M
Gomelsky
Laurent
L
Claret
Josée
J
Harel
Alain P
AP
Gobert
Christine
C
Martin
D000595:Amino Acid Sequence; D018441:Biofilms / Q000254:growth & development; D002465:Cell Movement / Q000502:physiology; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D019453:Escherichia coli O157 / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D044404:Genomic Islands; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009693:Nucleic Acid Hybridization; D010727:Phosphoric Diester Hydrolases / Q000172:deficiency* / Q000378:metabolism; D012313:RNA / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment
C062025:bis(3',5')-cyclic diguanylic acid; D012313:RNA; D010727:Phosphoric Diester Hydrolases; D006152:Cyclic GMP