TY - JOUR
T1 - Mutational analysis of the putative leukotoxin transport genes in actinobacillus actinomycetemcomitans
AU - Guthmiller, Janet M.
AU - Kolodrubetz, David
AU - Kraig, Ellen
PY - 1995/5
Y1 - 1995/5
N2 - The periodontal pathogen, Actinobacillus actinomycetemcomitans, produces leukotoxin, a protein that specifically lyses host defense cells. The leukotoxin is similar in sequence and operon organization to theEscherichia coliα-hemolysin and other members of the RTX family of toxins. However, unlike the other RTX toxins, theA. actinomycetemcomitansleukotoxin is not secreted from the cell and instead remains associated with the outer membrane. Nonetheless, theA. actinomycetemcomitans lktoperon contains two genes, lktBandlktD, that appear analagous to the toxin localization genes found in the other Gram-negative bacteria. Thus, to determine the roles of these putative transport genes inA. actinomycetemcomitans, we have used insertional mutagenesis to generate mutant strains lacking functional LktB and/or LktD. When eitherlktDor bothlktBandlktDwere inactivated, the level of detectable leukotoxin protein in the cell decreased significantly. However, thelktBandlktDmutations had no effect on the levels of leukotoxin RNA. Thus, the lack of LktB and LktD proteins must affect LktA synthesis post-transcriptionally. It is proposed that this is an indirect effect of leukotoxin mislocalization inlktB-andlktD-mutants. Finally, analysis of the mutants revealed that LktB and LktD are not essential for the formation of extracellular membrane vesicles inA. actinomycetemcomitans.
AB - The periodontal pathogen, Actinobacillus actinomycetemcomitans, produces leukotoxin, a protein that specifically lyses host defense cells. The leukotoxin is similar in sequence and operon organization to theEscherichia coliα-hemolysin and other members of the RTX family of toxins. However, unlike the other RTX toxins, theA. actinomycetemcomitansleukotoxin is not secreted from the cell and instead remains associated with the outer membrane. Nonetheless, theA. actinomycetemcomitans lktoperon contains two genes, lktBandlktD, that appear analagous to the toxin localization genes found in the other Gram-negative bacteria. Thus, to determine the roles of these putative transport genes inA. actinomycetemcomitans, we have used insertional mutagenesis to generate mutant strains lacking functional LktB and/or LktD. When eitherlktDor bothlktBandlktDwere inactivated, the level of detectable leukotoxin protein in the cell decreased significantly. However, thelktBandlktDmutations had no effect on the levels of leukotoxin RNA. Thus, the lack of LktB and LktD proteins must affect LktA synthesis post-transcriptionally. It is proposed that this is an indirect effect of leukotoxin mislocalization inlktB-andlktD-mutants. Finally, analysis of the mutants revealed that LktB and LktD are not essential for the formation of extracellular membrane vesicles inA. actinomycetemcomitans.
KW - A. actinomycetemcomitans
KW - IktB
KW - IktD
KW - Insertional mutagenesis
KW - Leukotoxin
UR - http://www.scopus.com/inward/record.url?scp=0029152281&partnerID=8YFLogxK
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U2 - 10.1006/mpat.1995.0028
DO - 10.1006/mpat.1995.0028
M3 - Article
C2 - 7476096
AN - SCOPUS:0029152281
VL - 18
SP - 307
EP - 321
JO - Microbial Pathogenesis
JF - Microbial Pathogenesis
SN - 0882-4010
IS - 5
ER -