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Table 1
Group I introns in bacteria and phage that encode homing endonuclease genes (HEGs)
HEG family	Organism^a	Taxonomy^b	Gene^c	rDNA insertion site^d	Intron size (nt)	HE size (aa) ^e	Functional HEs^f	Accession number

LAGLIDADG
	* Synechococcus sp. C9	Cyanobacteria	LSU	L1917	743	181		DQ421380
	Thermotoga subterranea	Thermotogae	LSU	L1917	774	168		AJ556793
	Simkania negevensis	Chlamydiae	LSU	L1931	654	143		U68460
	* Synechococcus lividus (strain C1)	Cyanobacteria	LSU	L1931	675	162		DQ421379
	* Synechococcus sp. C9	Cyanobacteria	LSU	L1931	666	167		DQ421380
	Thermotoga naphthophila	Thermotogae	LSU	L1931	699	162		AJ556785
	Thermotoga neapolitana	Thermotogae	LSU	L1931	700	162		AJ556784
	Thermotoga petrophila	Thermotogae	LSU	L1931	698	162		AJ556786
	Coxiella burnetii	Proteobacteria	LSU	L1951	720	157		AE016828
	* Synechococcus lividus (strain C1)	Cyanobacteria	LSU	L2593	744	189		DQ421379
	* Synechococcus sp. C9	Cyanobacteria	LSU	L2593	748	159		DQ421380
	Thermosynechococcus elongatus	Cyanobacteria	LSU	L2593	745	175		AP005376
GIY-YIG
	● Escherichia coli phage T4	Phage	sunY/nrdD	-	1033	258	I-TevII	NC_000866
	● Escherichia coli phage T4	Phage	td	-	1017	245	I-TevI	NC_000866
	Bacillus mojavensis	Firmicutes	thyA		1122	266	I-BmoI	AF321518
	Bacillus subtilis phage β22	Phage	thy	-	392	pseudo		L31962
	○ Bacillus anthracis	Firmicutes	nrdE (prophage)	-	1102	253	I-BanI	NC_003997
H-N-H
	● T-even phage RB3	Phage	nrdB	-	1090	269	I-TevIII	X59078
	Bacillus phage SPO1	Phage	DNA pol	-	882	174	I-HmuI	M37686
	Bacillus phage SP82	Phage	DNA pol	-	915	185	I-HmuII	U04812
	Bacillus phage ϕe	Phage	DNA pol	-	903	181		U04813
	Escherichia coli phage ΦI	Phage	DNA pol	-	601	131	I-TslI	AY769989
	Escherichia coli phage W31	Phage	DNA pol	-	601	131	I-TslI	AY769990
	Bacillus phage Spbeta	Phage	bnrdF	-	808	173		NC_001884
	Staphylococcal phage Twort	Phage	nrdE	-	1087	243	I-TwoI	AF485080
	Bacillus thuringiensis phage Bastille	Phage	DNA pol	-	853	188	I-BasI	AY256517
	Streptococcus thermophilus phage J1	Phage	Lysin	-	1013	253		AF148566
	Lactobacillus delbrueckii subsp. lactis phage LL-H	Phage	terL	-	837	168		L37351
PD-(D/E)XK
	Synechocystis sp. PCC 6803	Cyanobacteria	tRNA-fMet	-	655	150	I-Ssp6803I	U10482

^aOrganism names. Intron hosts reported in this study are marked with asterisks. Filled circles indicate that homologous introns are found in closely related T-even-like phages [50] and the open circle indicates that homologous introns exist in closely related Bacillus species and strains [4], but are not included in this table. ^bClassification of organisms follows that of the NCBI (National Center for Biotechnology Information) GenBank. ^cThe gene in which the intron is inserted. ^dThe numbering reflects the Escherichia coli genic position. ^eHE length in amino acids (aa). HE gene fragments are indicated (pseudo). ^fActive HE proteins that cut the intron minus target sites.
Haugen et al. BMC Evolutionary Biology 2007 7:159 doi:10.1186/1471-2148-7-159

Table 1