Nucleotide sequence and expression of a novel pectate lyase gene (pel-3) and a closely linked endopolygalacturonase gene (peh-1) of Erwinia carotovora subsp. carotovora 71.
Our previous genetic analysis (J. W. Willis, J. K. Engwall, and A. K. Chatterjee, Phytopathology 77:1199-1205, 1987) had revealed a tight linkage between pel-3 (pel, pectate lyase gene) and peh-1 (peh, polygalacturonase gene) within the chromosome of Erwinia carotovora subsp. carotovora 71. Nucleotide sequencing, transcript assays, and expression of enzymatic activities in Escherichia coli have now confirmed that a 3,500-bp segment contains the open reading frames (ORFs) for Pel-3 and Peh-1. The 1,041-bp pel-3 ORF and the 1,206-bp peh-1 ORF are separated by a 579-bp sequence. The genes are transcribed divergently from their own promoters. In E. coli and E. carotovora subsp. carotovora 71, peh-1 is better expressed than pel-3. However, plant signals activate the expression of both the genes in E. carotovora subsp. carotovora. A consensus integration host factor (IHF)-binding sequence upstream of pel-3 appears physiologically significant, since pel-3 promoter activity is higher in an E. coli IHF+ strain than in an IHF- strain. While peh-1 has extensive homology with plant and bacterial peh genes, pel-3 appears not to have significant homology with the pel genes belonging to the pelBC, pelADE, or periplasmic pel families. Pel-3 also is unusual in that it is predicted to contain an ATP- and GTP-binding site motif A (P-loop) not found in the other Pels.
Liu
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Y
Department of Plant Pathology, University of Missouri, Columbia 65211.
Chatterjee
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A
Chatterjee
A K
AK
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008040:Genetic Linkage; D007763:Lac Operon; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D016973:Pectobacterium carotovorum / Q000201:enzymology* / Q000235:genetics*; D011096:Polygalacturonase / Q000235:genetics*; D011133:Polysaccharide-Lyases / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D004269:DNA, Bacterial; D011096:Polygalacturonase; D011133:Polysaccharide-Lyases; C023911:pectate lyase