Chromosomal integration of Tn5253 occurs downstream of a conserved 11-bp sequence of the rbgA gene in Streptococcus pneumoniae and in all the other known hosts of this integrative conjugative element (ICE)

Table 2 PCR quantification of Tn5253 circular forms and reconstituted attB integration sites in Tn5253-carrying transconjugants

Strain	Genetic background	Circular Forms	Reconstituted attB Site	Conjugation Frequency Mean (Range)^a
FR39	S. pneumoniae A66	2.0 × 10⁻⁵ ± 1.9 × 10⁻⁵	<6.9 × 10⁻⁶ ± 7.1 × 10⁻⁸	4.4 × 10⁻⁷ (3.2 × 10⁻⁷ - 5.8 × 10⁻⁷)
FR54	S. pneumoniae TIGR4	<3.6 × 10⁻⁵ ± 2.6 × 10⁻⁶	<3.5 × 10⁻⁴ ± 2.6 × 10⁻⁵	<9.9 × 10⁻⁸ (<9.6 × 10⁻⁸ - <1.3 × 10⁻⁷)
FR56	S. pneumoniae SP18-BS74	1.2 × 10⁻² ± 7.5 × 10⁻⁵	1.9 × 10⁻³ ± 1.0 × 10⁻⁴	6.1 × 10⁻⁶ (3.5 × 10⁻⁶ - 9.5 × 10⁻⁶)
FR67	S. agalactiae H36B	2.9 × 10⁻⁵ ± 8.7 × 10⁻⁶	3.0 × 10⁻⁴ ± 1.0 × 10⁻⁴	1.1 × 10⁻⁶ (3.2 × 10⁻⁷ - 2.1 × 10⁻⁶)
FR68	S. pyogenes SF370	3.0 × 10⁻⁵ ± 1.0 × 10⁻⁵	3.7 × 10⁻⁵ ± 6.2 × 10⁻⁶	9.5 × 10⁻⁴ (3.3 × 10⁻⁵ - 2.6 × 10⁻³)
FR43	S. gordonii V288	6.5 × 10⁻⁵ ± 4.4 × 10⁻⁵	7.9 × 10⁻⁵ ± 1.2 × 10⁻⁵	8.3 × 10⁻⁷ (1.2 × 10⁻⁷ - 2.0 × 10⁻⁶)
FR49	E. faecalis OG1SS	1.4 × 10⁻⁴ ± 9.2 × 10⁻⁵	6.8 × 10⁻³ ± 1.0 × 10⁻⁴	<1.8 × 10⁻⁸ (<1.0 × 10⁻⁹ - <3.9 × 10⁻⁸)
FR50	E. faecalis JH2-2	<2.7 × 10⁻⁷ ± 7.5 × 10⁻⁸	1.7 × 10⁻² ± 1.3 × 10⁻³	<2.7 × 10⁻⁸ (<9.9 × 10⁻⁹ - <5.0 × 10⁻⁸)

^aFrequency refers to mating experiments where S. pneumoniae FP10 or FP11was the conjugation recipient [29]; conjugation frequency is expressed as
CFU of transconjugants per CFU of donors; each result is the mean of at least three mating experiments

ISSN: 1759-8753