TABLE 1 .

ORFs within an ~17.3-kb region of pCS1-1 predicted to encode major components of a Gram-positive conjugation system^a

Gene	Predicted function	Bioinformatic evidence
cstD4	Coupling protein	C terminus containing pfam12696 domain; mediation of interaction of coupling proteins with cognate relaxase (34); two predicted N-terminal transmembrane helices (3); Walker A and B motifs (61)
cstB6	Membrane pore component	Nonspecific/superfamily domain (TIGR02783) found in TrbL (mating pair formation pore-forming protein) of trb conjugation locus (34); 5–7 predicted transmembrane domains within the C-terminal half, 698 aa in length, and therefore most similar to class DELTA VirB6-like proteins (3)
cstB4	VirB4-like ATPase	Walker A and B motifs (62); multiple domains (pfam12846, TIGR02746, PRK13721) associated with conjugation-related ATPases (34)
cstB1	Peptidoglycan hydrolase	Short (22-aa) N-terminal sequence before single transmembrane domain; putative class ALPHA lytic transglycolylase (3); N-terminal nonspecific domains (pfam01464, cd00254) associated with lytic transglycolylases (34); C-terminal catalytic NlpC/P60 domain (34), also present in peptidoglycan hydrolase TcpG from pCW3 conjugation system (63, 64)
cstD2	Relaxase	Containing N-terminal catalytic tyrosine motifs and histidine triad motif of MobMG family of relaxases (clusters within MobP relaxase family) (35, 65)

^aGene names and predicted functions of their products are shown. The bioinformatic evidence for each ORF’s predicted function is provided together with appropriate references. aa, amino acid.