Title page for ETD etd-02012006-141753


Type of Document Dissertation
Author Kyostio, Sirkka R. M.
URN etd-02012006-141753
Title Erwinia carotovora extracellular proteases : characterization and role in soft rot
Degree PhD
Department Plant Physiology
Advisory Committee
Advisor Name Title
Cramer, Carole L. Committee Co-Chair
Lacy, George H. Committee Co-Chair
Johnson, John L. Committee Member
Potts, Malcolm Committee Member
Veilleux, Richard E. Committee Member
Keywords
  • Bacterial soft rot of potato.
Date of Defense 1990-12-03
Availability restricted
Abstract

Erwinia carotovora subsp. carotovora (Ecc) strain EC14, a Gram-negative bacterium, causes soft rot on several crops, including potato. Maceration of potato tuber tissue is caused by secreted pectolytic enzymes. Other cell-degrading enzymes may also have roles in pathogenesis, including cellulases, phospholipases, and protease(s). The objectives of this research were to (1) characterize Ecc extracellular protease (Prt) and (2) elucidate its role in potato soft rot. A gene encoding a Prt, prt1, was cloned from cosmid pCA7 containing Ecc genomic DNA into plasmid pSK1. Escherichia coli transformed with pSK1 or pSK23, a subclone of pSK1, produced intracellularly a 38 kDa Prt with the same pI (4.8) as the secreted Ecc Prt. Prt1 activity produced by E.coli/pSK23 was inhibited by phenanthroline, which inhibits Zn-metalloproteases, but not by Ecc intracellular proteins. Analysis of deletion mutants indicated a 1.2 kb region necessary for Prt1 production. Sequencing of the pSK1 insert revealed a 1,041 bp open reading frame (ORF1) corresponding to the prtl region. ORF1 encodes a putative polypeptide of 347 amino acids with a total molecular mass of 38.8 kDa.

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