Comparative genomics of the pathogenic ciliate Ichthyophthirius multifiliis, its free-living relatives and a host species provide insights into adoption of a parasitic lifestyle and prospects for disease control

Table 5 Protease complements in Ich and other model organisms

	Catalytic class						Percentage of the
Organism	Aspartic	Cysteine	Metallo	Serine	Threonine	Total	proteome^a
Ichthyophthirius multifiliis	14 (5.5%)	81 (31.9%)	119 (46.9)	25 (9.9%)	15 (5.9%)	254	3.1
Paramecium tetraurelia	48 (8.3%)	225 (38.9%)	168 (29.1%)	95 (16.4%)	42 (7.3%)	578	1.5
Tetrahymena thermophila ^b	43 (9.0%)	211 (44.0%)	139 (28.9%)	73 (15.2%)	14 (2.9%)	480	1.7
Plasmodium falciparum	17 (10.5%)	33 (34.7%)	21 (22.1%)	16 (16.9%)	15 (15.8%)	95	1.8
Neurospora crassa	19 (8.1%)	41 (17.4%)	81 (34.5%)	75 (31.9%)	19 (8.1%)	235	2.4
Saccharomyces cerevisiae	19 (11.1%)	41 (24.0%)	57 (33.3%)	38 (22.2%)	16 (9.4%)	171	2.4
Caenorhabditis elegans	27 (5.6%)	125 (25.9%)	190 (39.4%)	115 (23.9%)	25 (5.2%)	482	2.4
Drosophila melanogaster	46 (6.2%)	86 (11.5%)	207 (27.7%)	373 (49.9%)	35 (4.7%)	747	5.4
Homo sapiens	320 (29.3%)	190 (17.4%)	252 (23.0%)	291 (26.6%)	41 (3.7%)	1,094	4.5
Arabidopsis thaliana	233 (27.6%)	162 (19.2%)	112 (13.3%)	306 (36.2%)	31(3.7%)	849	3.1

Values in parentheses are the percentage of the individual catalytic class in the protease complement. ^aThe percentage of the whole genome that encodes putative proteases. ^bThe distributions of T. thermophila and P. falciparum are based on Eisen et al. [11] and Wu et al. [60], respectively. The distributions of the other model organisms are based on the results published in Merops database.

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