Chemical Mutagenesis, Isolation and Characterization of Non-Haemolytic - Abstract
A collection of non-haemolytic M. haemolytica mutants were generated by EMS (ethyl methanesulfonate) mutagenesis. Total proteins from these mutants were examined by Western immunoblot analysis using antibodies specific for the leukotoxin LktA. LktAwas not detected in some of the mutants as expected; however, LktA was detected in several mutants in spite of a non-haemolytic phenotype. These mutants could have a defect in any one of the four genes, or elsewhere in the genome suggesting other factors may be required for fully functional leukotoxin production. The lktA gene from mutant 36 was isolated by PCR and sequenced. Mutant 36 was found to have a G-C to A-T substitution resulting in codon change from GAG to AAG and E470K amino acid substitution.