Table 1. Properties of putative conjugative and mobilizable transposons in C. difficile.

Strain	Element	Genome excision	Properties	CDS start	CDS stop	Size (kb)	Percent G+C	Transfer frequency (σ)	Genbank accession number (if appropriate)
630	CTn1	Yes		CD0355	CD0386	28.9	38.6	7.0*10−9 (9.0*10−9), 2.0*10−8 (1.7*10−8)
	CTn2	Yes		CD0408	CD0436	42.2	35.1	2.1*10−4 (5.5*10−4)
	Tn5397	Yes	TcR	CD0496	CD0511	20.7	38.3
	CTn4	Yes		CD1091	CD1118	30.5	46.6	2.3*10−6 (4.2*10−6)
	CTn5	Yes		CD1845	CD1878a	45.6	32.7	2.8*10−5 (2.6*10−5)
	CTn6	No		CD3326	CD3348	21.3	42.8
	CTn7	Yes		CD3370	CD3392	29.2	40.9	9.6*10−9 (4.4*10−9)
	Tn5398	ND	ErmR	CD2001	CD2010b	9.6	35.4
R20291	CTn1-like	No		3453	3475	27.2	39.9
	Tn6103	Yes		1740	1809	84.9	41.2	<10−11	BK008007, JF422666
	Tn6104	Yes		1744	1764	15.6	48.2
	Tn6105	No		1765	1775	15.8	49.8
	Tn6106	No		1777	1788	11.3	49.9
CD196	CTn1-like	ND		3407	3429	27.2	39.7
QCD-23M63	Tn6073	Yes		3137	2962	29.1	39.3		BK008006, JF422665
	CTn4-like	ND		4815	4970	25.0	45.0
	Tn6107	Yes		16791	16991	50.5	33.5		BK008008, JF422667
QCD-63Q42	CTn1-like	NA		7272	7692	71.7	42.0
	CTn1-like	NA		9214	9039	30.9	39.7
	CTn5-like	NA		17051	17266	52.2	32.4
	Tn6115	NA		7732	7787	13.6	47.2
	CTn7-like	NA		17276	17431	29.6	40.5
ATCC-43255	CTn1-like	No		6310	6090	38.5	37.7
	Tn5398-like	ND		10502	10527	5.4	36.9
QCD-37X79	CTn1-like	NA		18585	18425	27.2	39.4
	CTn5-like	NA		16948	17243	58.0	37.8
QCD-66C26	CTn1-like	No		18275	18120	27.2	39.4
	Tn6110	Yes		16663	16958	58.0	37.8		BK008009, JF422668
QCD-32G58	CTn1-like	No		4196	4166	27.2	39.4
	Tn6111	Yes		2165	3914	53.4†	37.9†		JF422669
QCD-76W55	CTn1-like	NA		18479	18319	27.2	39.6
QCD-97B34	CTn1-like	NA		18008	17853	27.2	39.5

Tc: tetracycline, Erm: erythromycin, ^S: sensitive, ^R: resistant. Genome excision ND = not determined, NA = not available. σ: standard deviation.

^† = Sequence of the element was not joined in assembled genome, size and G+C percentage are estimates. The sequences of novel circular intermediates were deposited in Genbank with the accession numbers given. Transfer frequency is calculated as the number of transconjugant cells per donor cell. Two transfer frequencies are reported for CTn1 marked with the Clostron in two different genes, CD0364 and CD0386, respectively.