Purification and characterization of a novel esterase (beta-hydroxypalmitate methyl ester hydrolase) and prevention of the expression of virulence by Ralstonia solanacearum.
OBJECTIVE
To screen novel micro-organisms and enzymes capable of degrading 3-hydroxypalmitic acid methyl ester (3-OH PAME), the quorum-sensing signal molecule (quormone), which regulates the virulence of Ralstonia solanacearum.


RESULTS
Ideonella sp. 0-0013, a betaproteobacterium isolated from soil using the selective-enrichment culture method, was grown on plates containing 3-OH PAME as its main carbon source. beta-Hydroxypalmitate methyl ester hydrolase (betaHPMEH) purified from the supernatant of the Ideonella sp. 0-0013 culture exhibited high hydrolysing activity towards the ester bond of 3-OH PAME and eliminated the 3-OH PAME activity, thereby reducing the virulence of R. solanacearum. An Escherichia coli transformant of the betahpmeh gene expression vector degraded 3-OH PAME, and the crude enzyme from the transformant inhibited in vitro production of the R. solanacearum exopolysaccharide (EPS).


CONCLUSIONS
The ability of betaHPMEH to hydrolyse 3-OH PAME inhibited the production of EPS by the R. solanacearum wild-type strain, indicating that betaHPMEH inhibits the effects of activation of virulence genes. This ability will be potentially useful for pest control of the wilt disease caused by this bacterium.


CONCLUSIONS
This enzyme is the first protein that has been found to degrade a quormone other than N-acyl homoserine lactone.
Shinohara
M
M
National Institute of Vegetable and Tea Science, National Agricultural Research Organization, Chita, Aichi, Japan. shsh@affrc.go.jp
Nakajima
N
N
Uehara
Y
Y
D000595:Amino Acid Sequence; D000898:Antibiosis / Q000502:physiology*; D001431:Bacteriological Techniques; D001483:Base Sequence; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D003001:Cloning, Molecular; D042621:Comamonadaceae / Q000201:enzymology / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010169:Palmitic Acids / Q000378:metabolism; D010572:Pest Control, Biological / Q000379:methods; D053038:Quorum Sensing / Q000187:drug effects; D043368:Ralstonia solanacearum / Q000378:metabolism / Q000472:pathogenicity*; D012988:Soil Microbiology; D013379:Substrate Specificity; D014774:Virulence / Q000235:genetics
D010169:Palmitic Acids; C108229:3-hydroxypalmitic acid; D002265:Carboxylic Ester Hydrolases; C525440:beta-hydroxypalmitate methyl ester hydrolase, Ralstonia solanacearum