Cloning, expression, and characterization of the lon gene of Erwinia amylovora: evidence for a heat shock response

• Published in: Journal of Bacteriology 1995-02, Vol.177 (4), p.932-937
• Main Authors: Eastgate, J.A. (University of Leicester, Leicester, UK.), Taylor, N, Coleman, M.J, Healy, B, Thompson, L, Roberts, I.S
• Format: Article
• Language: English
• Subjects: ACILTRANSFERASA; ACYLTRANSFERASE; ADN RECOMBINADO; ADN RECOMBINE; Amino Acid Sequence; ATP-Dependent Proteases; Bacillus brevis; Bacteriology; Base Sequence; CHLORAMPHENICOL; CLONACION; CLONAGE; Cloning, Molecular; CLORAMFENICOL; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; Erwinia - enzymology; Erwinia - genetics; ERWINIA AMYLOVORA; Escherichia coli; Escherichia coli - genetics; Escherichia coli Proteins; ESTRES TERMICO; EXPRESION GENICA; EXPRESSION DES GENES; GENE; Gene Expression Regulation, Bacterial; GENES; Genes, Bacterial - genetics; GENETICA; GENETIQUE; Heat-Shock Proteins - biosynthesis; Heat-Shock Proteins - genetics; Hot Temperature; INFECCION; INFECTION; MALUS PUMILA; Molecular Sequence Data; MUTACION; Mutagenesis, Insertional; MUTANT; MUTANTES; MUTATION; Myxococcus xanthus; Promoter Regions, Genetic - genetics; PROTEASAS; PROTEASE; Protease La; Proteins; Recombinant Proteins - biosynthesis; RNA, Messenger - genetics; SECUENCIA NUCLEICA; Sequence Analysis, DNA; Sequence Homology, Nucleic Acid; SEQUENCE NUCLEIQUE; Serine Endopeptidases - biosynthesis; Serine Endopeptidases - genetics; STRESS THERMIQUE
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.177.4.932-937.1995

The gene encoding the Lon protease of Erwinia amylovora has been cloned by complementation of an Escherichia coli lon mutant. Analysis of the determined nucleotide sequence of the lon gene revealed extensive homology to the nucleotide sequences of cloned lon genes from E. coli, Myxococcus xanthus, and Bacillus brevis. The predicted amino acid sequence of the E. amylovora Lon protease was 94, 59, and 54% identical to the predicted amino acid sequences of the Lon proteases of E. coli, M. xanthus, and B. brevis, respectively. The -10 and -35 promoter regions of the cloned lon gene had extensive homology to the respective consensus sequences of E. coli heat shock promoters. Promoter mapping of the lon gene located the start site 7 bases downstream of the -10 region. Cloning of the lon promoter upstream of a cat reporter gene demonstrated that expression of the E. amylovora lon gene was inducible by a heat shock. This is the first demonstration of a heat shock-regulated gene in E. amylovora. Site-directed mutagenesis of the -10 region of the lon promoter confirmed that the heat shock expression of the E. amylovora lon gene may be mediated by a sigma 32-like factor. Insertional inactivation of the E. amylovora chromosomal lon gene confirmed that the lon gene was not essential for either vegetative growth or infection of apple seedlings. E. amylovora lon mutants had increased sensitivity to UV irradiation and elevated levels of extracellular polysaccharide, suggesting comparable roles for the Lon proteases in both E. amylovora and E. coli