title: Genomic distribution and functions of uptake signal sequences in Actinobacillus actinomycetemcomitans.
abstract: Actinobacillus actinomycetemcomitans is naturally competent for transformation, with a transformation system similar to that of Haemophilus influenzae that preferentially takes up DNA bearing uptake signal sequences (USS) with the same 9-base USS core. This study examined the function of the extended 29-base USS, which comprises a highly conserved 1st region (containing the 9-base core) and 2nd and 3rd semi-conserved AT-rich regions, in transformation of A. actinomycetemcomitans. Transformation frequency was not affected by either location (in middle or at 5' end) or quantity (one or two) of USS in donor DNA. Relative transformation efficiencies (in comparison to the positive control) were 28-67 % for linear DNA with single-base mutations in the USS 1st region, and 47 % and 73 %, respectively, for linear DNA with USS that contained either a non-consensus 2nd or a non-consensus 3rd region. Plasmids with a stand-alone 1st or a stand-alone 2nd-3rd region exhibited 21 % and 6 % relative transformation efficiencies, respectively. It was also noted that A. actinomycetemcomitans and H. influenzae were similar in the frequencies and distribution patterns of USS in their genomes. In conclusion, all three regions of the extended 29-base USS are required for optimum transformation in A. actinomycetemcomitans.
authors.affiliation: Division of Primary Oral Health Care, University of Southern California School of Dentistry, 925 W 34th Street, Room 4107, Los Angeles, CA 90089-0641, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Microbiology and Immunology, University of Oklahoma, Oklahoma City, OK 73190, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Orvis
authors.affiliation: Department of Microbiology and Immunology, University of Oklahoma, Oklahoma City, OK 73190, USA.
authors.forename: David
authors.initials: D
authors.lastname: Dyer
authors.affiliation: Division of Primary Oral Health Care, University of Southern California School of Dentistry, 925 W 34th Street, Room 4107, Los Angeles, CA 90089-0641, USA.
authors.forename: Casey
authors.initials: C
authors.lastname: Chen
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000235:genetics* / Q000378:metabolism; D016680:Genome, Bacterial; D021382:Protein Sorting Signals / Q000502:physiology*; D014169:Transformation, Bacterial
chemical_list: D021382:Protein Sorting Signals