This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cha, J. S. Articles by Kado, C. I. Search for Related Content PubMed PubMed Citation Articles by Cha, J. S. Articles by Kado, C. I. Agricola Articles by Cha, J. S. Articles by Kado, C. I.

 Previous Article  |  Next Article 

Appl. Environ. Microbiol., 01 1997, 71-76, Vol 63, No. 1
Copyright © 1997, American Society for Microbiology

Identification and characterization of a Pantoea citrea gene encoding glucose dehydrogenase that is essential for causing pink disease of pineapple

JS Cha, C Pujol and CI Kado
Department of Plant Pathology, University of California, Davis 95616, USA.

Pantoea citrea, a member of the family Enterobacteriaceae, causes pink disease of pineapple, whose symptom is characterized by the formation of pink to brown discolorations of the infected portions of the pineapple fruit cylinder upon canning. Molecular genetic approaches were applied to elucidate the mechanism responsible for this fruit discoloration. A P. citrea mutant strain, CMC6, defective in its ability to cause pink disease and fruit discoloration, was generated by nitrosoguanidine mutagenesis. A DNA fragment that restored these activities was isolated by screening a genomic cosmid library of P. citrea. A large open reading frame of 2,361 bp, identified by nucleotide sequencing of a subclone of the complementing DNA, showed high similarities to identified genes encoding glucose dehydrogenase (GDH) in Escherichia coli, Acinetobacter calcoaceticus, and Gluconobacter oxydans. The predicted amino acid sequence of GDH of P. citrea was identical to known GDHs in these bacteria by 54, 44, and 34%, respectively. GDH of P. citrea has a predicted molecular mass of 86.2 kDa, contains a conserved binding domain for the cofactor pyrroloquinoline quinone, and possesses GDH activity as demonstrated by biochemical assay. GDH is the key branch point enzyme leading to the biosynthesis of gluconate, which in turn serves as the substrate leading to the formation of 2-ketogluconate, 2,5-diketogluconate, 6- phosphogluconate, and 2-keto-6-phosphogluconate. Addition of gluconate to CMC6 restores the juice- and fruit-discoloring activity. Although the pigments formed by heating (or canning) have not been identified, it is clear that GDH is one of the enzymes required for pigment formation leading to pink disease.

This article has been cited by other articles:

• Pujol, C. J., Kado, C. I. (2000). Genetic and Biochemical Characterization of the Pathway in Pantoea citrea Leading to Pink Disease of Pineapple. J. Bacteriol. 182: 2230-2237 [Abstract] [Full Text]