October
2005
, Volume
18
, Number
10
Pages
1,090
-
1,098
Authors
Olaf
Kaup
,
Ines
Gräfen
,
Eva-Maria
Zellermann
,
Rudolf
Eichenlaub
,
and
Karl-Heinz
Gartemann
Affiliations
Department of Genetechnology/Microbiology, University of Bielefeld, Universitaetsstr. 25, 33615 Bielefeld, Germany
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RelatedArticle
Accepted 6 June 2005.
Abstract
The insertion site of a transposon mutant of Clavibacter michiganensis subsp. michiganensis NCPPB382 was cloned and found to be located in the gene tomA encoding a member of the glycosyl hydrolase family 10. The intact gene was obtained from a cosmid library of C. michiganensis subsp. michiganensis. The deduced protein TomA (543 amino acids, 58 kDa) contains a predicted signal peptide and two domains, the N-terminal catalytic domain and a C-terminal fibronectin III-like domain. The closest well-characterized relatives of TomA were tomatinases from fungi involved in the detoxification of the tomato saponin α-tomatine which acts as a growth inhibitor. Growth inhibition of C. michiganensis subsp. michiganensis by α-tomatine was stronger in the tomA mutants than in the wild type. Tomatinase activity assayed by deglycosylation of α-tomatine to tomatidine was demonstrated in concentrated culture supernatants of C. michiganensis subsp. michiganensis. No activity was found with the tomA mutants. However, neither the transposon mutant nor a second mutant constructed by gene disruption was affected in virulence on the tomato cv. Moneymaker.
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© 2005 The American Phytopathological Society