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Structural analysis of the pehA gene and characterization of its protein product, endopolygalacturonase, of Erwinia carotovora subspecies carotovora
Author(s) -
Saarilahti H. T.,
Heino P.,
Pakkanen R.,
Kalkkinen N.,
Palva I.,
Palva E. T.
Publication year - 1990
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1990.tb00676.x
Subject(s) - biology , erwinia , subspecies , gene , product (mathematics) , gene product , microbiology and biotechnology , genetics , gene expression , ecology , geometry , mathematics
Summary A clone producing a potygalacturonase (EC 3.2.1.15) in Escherichia coli was isolated from a genomic library of Erwinia carotovora subspecies carotovora constructed in pUC18. The DNA segment carrying the corresponding structural gene, named pehA , contained an open reading frame (ORF) encoding a 402‐amino‐acid (aa) polypeptide with an M r of 42849. In E. carotovora the polygalacturonase was synthesized with a 26‐aa cleavable signal peptide. The mature 376‐aa PehA had a calculated M r of 40064 and a pi of 10.19. The pH optimum of the enzyme was about 5.5 and the temperature optimum was in the range 35–45 ° C. Analysis of the reaction products of poly‐galacturonic acid hydrolysis indicated that the PehA protein is an endopolygalacturonase. No similarity was observed between the aa sequences of PehA and other pectic enzymes of Erwinias. However, substantial similarity was detected within the C ‐terminal portions of PehA and a previously described tomato polygalacturonase, suggesting that the bacterial and eukaryotic potygalacturonases may have a common origin.