Yuting Alice Yang1, Ya-An Cheng2, Casey Chen3. 1. Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry, University of Southern California, 925 W 34th street, Los Angeles, CA 90089, USA. Electronic address: yutingy@usc.edu. 2. Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry, University of Southern California, 925 W 34th street, Los Angeles, CA 90089, USA. Electronic address: yaanchen@gmail.com. 3. Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry, University of Southern California, 925 W 34th street, Los Angeles, CA 90089, USA. Electronic address: ccchen@usc.edu.
Abstract
OBJECTIVE: To test the hypothesis that virulence genes of Aggregatibacter actinomycetemcomitans can be expressed and confer fitness advantages in the closely related Aggregatibacter aphrophilus. DESIGN: Clinical isolates of A. aphrophilus were screened for natural competence with marked genomic DNA from A. actinomycetemcomitans and A. aphrophilus. The gene katA of A. actinomycetemcomitans D7S-1 and its flanking regions were constructed and inserted into a comparable locus in the genome of a naturally competent A. aphrophilus strain by a markerless protocol via natural transformation. Mutants of A. actinomycetemcomitans with or without katA were also constructed by a similar protocol. Discs soaked with either 0.03% hydrogen peroxide or broth culture of Streptococcus gordonii Challis were placed on the agar with cultures of A. actinomycetemcomitans or A. aphrophilus. The size of the growth inhibition zone associated with the disc was measured after 2-day culture. RESULTS: Five of the 13A. aphrophilus strains exhibited a transformation frequency of 10-6 or higher. The intra- and inter-species transformation frequencies were comparable. The inhibition zones for katA-negative strains of A. actinomycetemcomitans or A. aphrophilus were 3- to 7-fold larger than those associated with katA-positive strains (p<0.05). CONCLUSIONS: There was no apparent species barrier for the transfer and expression of A. actinomycetemcomitans katA in A. aphrophilus. The inserted A. actinomycetemcomitans-specific katA gene in A. aphrophilus strain NJ8700 conferred resistance to inhibition by hydrogen peroxide or S. gordonii. The potential to swap genes between these two closely related oral species may be an alternative approach for investigating the virulence determinants of A. actinomycetemcomitans.
OBJECTIVE: To test the hypothesis that virulence genes of Aggregatibacter actinomycetemcomitans can be expressed and confer fitness advantages in the closely related Aggregatibacter aphrophilus. DESIGN: Clinical isolates of A. aphrophilus were screened for natural competence with marked genomic DNA from A. actinomycetemcomitans and A. aphrophilus. The gene katA of A. actinomycetemcomitans D7S-1 and its flanking regions were constructed and inserted into a comparable locus in the genome of a naturally competent A. aphrophilus strain by a markerless protocol via natural transformation. Mutants of A. actinomycetemcomitans with or without katA were also constructed by a similar protocol. Discs soaked with either 0.03% hydrogen peroxide or broth culture of Streptococcus gordonii Challis were placed on the agar with cultures of A. actinomycetemcomitans or A. aphrophilus. The size of the growth inhibition zone associated with the disc was measured after 2-day culture. RESULTS: Five of the 13A. aphrophilus strains exhibited a transformation frequency of 10-6 or higher. The intra- and inter-species transformation frequencies were comparable. The inhibition zones for katA-negative strains of A. actinomycetemcomitans or A. aphrophilus were 3- to 7-fold larger than those associated with katA-positive strains (p<0.05). CONCLUSIONS: There was no apparent species barrier for the transfer and expression of A. actinomycetemcomitans katA in A. aphrophilus. The inserted A. actinomycetemcomitans-specific katA gene in A. aphrophilus strainNJ8700 conferred resistance to inhibition by hydrogen peroxide or S. gordonii. The potential to swap genes between these two closely related oral species may be an alternative approach for investigating the virulence determinants of A. actinomycetemcomitans.
Authors: Maria Pia Di Bonaventura; Rob DeSalle; Mihai Pop; Niranjan Nagarajan; David H Figurski; Daniel H Fine; Jeffrey B Kaplan; Paul J Planet Journal: J Bacteriol Date: 2009-05-15 Impact factor: 3.490
Authors: Apollo Stacy; Jake Everett; Peter Jorth; Urvish Trivedi; Kendra P Rumbaugh; Marvin Whiteley Journal: Proc Natl Acad Sci U S A Date: 2014-05-13 Impact factor: 11.205