title: A temperature-sensitive DNA adenine methyltransferase mutant of Salmonella typhimurium.
abstract: A temperature-sensitive mutant of Salmonella typhimurium was isolated earlier after transposon mutagenesis with Tn10d Tet. The mutant D220 grows well at 28 degreesC but has a lower growth rate and forms filaments at 37 degreesC. Transposon-flanking fragments of mutant D220 DNA were cloned and sequenced. The transposon was inserted in the dam gene between positions 803 and 804 (assigned allele number: dam-231 : : Tn10d Tet) and resulted in a predicted ten-amino-acid-shorter Dam protein. The insertion created a stop codon that led to a truncated Dam protein with a temperature-sensitive phenotype. The insertion dam-231 : : Tn10d Tet resulted in a dam "leaky" phenotype since methylated and unmethylated adenines in GATC sequences were present. In addition, the dam-231 : : Tn10d Tet insertion rendered dam mutants temperature-sensitive for growth depending upon the genetic background of the S. typhimurium strain. The wild-type dam gene of S. typhimurium exhibited 82% identity with the Escherichia coli dam gene.
authors.affiliation: Centro de Estudios Farmacolígicos y Botánicos (CEFYBO-CONICET) and University of Buenos Aires, School of Medicine, Serrano 669, 1414 Buenos Aires, Argentina.
authors.forename: R
authors.initials: R
authors.lastname: Brawer
authors.forename: F D
authors.initials: FD
authors.lastname: Batista
authors.forename: O R
authors.initials: OR
authors.lastname: Burrone
authors.forename: D O
authors.initials: DO
authors.lastname: Sordelli
authors.forename: M C
authors.initials: MC
authors.lastname: Cerquetti
mesh_terms: D004251:DNA Transposable Elements / Q000235:genetics; D016133:Polymerase Chain Reaction; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000235:genetics* / Q000302:isolation & purification; D013696:Temperature
chemical_list: D004251:DNA Transposable Elements; C058693:Dam methyltransferase; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)