Comparative Analysis of Genome of Ehrlichia sp. HF, a Model Bacterium to Study Fatal Human Ehrlichiosis

BMC Genomics

Table 4 Potential pathogenic genes in Ehrlichia sp. HF, E. chaffeensis, E. muris subsp. muris, and E. muris subsp. eauclairensis

Organisms¹	EHF	ECH	EMU	EmCRT
Outer Membrane Proteins:
Omp-1/P28 family proteins	23	22	20	20
Omp85	+	+	+	+
OmpH	+	+	+	+
OmpA family protein	+	+	+	+
EtpE	+	+	+	+
Type IV Secretion System:
VirB1/B5	-	-	-	-
VirB2	+ (5)	+ (4)	+ (4)	+ (5)
VirB3	+	+	+	+
VirB4	+ (2)	+ (2)	+ (2)	+ (2)
VirB6	+ (4)	+ (4)	+ (4)	+ (4)
VirB7	+	+	+	+
VirB8	+ (2)	+ (2)	+ (2)	+ (2)
VirB9	+ (2)	+ (2)	+ (2)	+ (2)
VirB10/B11/D4	+	+	+	+
Putative T4SS Effectors:
Etf-1	+	+	+	+
Etf-2²	±	+	±	±
Etf-3	+	+	+	+
Type I Secretion System³	+	+	+	+
Twin-arginine Translocation (TAT) Pathway⁴	+	+	+	+
TRP Proteins
TRP32	+ (94 aa)	+ (198 aa)	+ (112 aa)	+ (105 aa)
TRP47	+ (255 aa)	+ (316 aa)	+ (228 aa)	+ (252 aa)
TRP120	+ (584 aa)	+ (548 aa)	+ (1288 aa)	+⁵
Ankyrin-repeat domain proteins	5	5	5	5
Two-Component Regulatory Systems:
PleC/PleD	+	+	+	+
NtrY/NtrX	+	+	+	+
CckA/CtrA	+	+	±⁶	+

¹Abbreviations: EHF, Ehrlichia sp. HF; EMU, E. muris subsp. muris AS145; ECH, E. chaffeensis Arkansas; EmCRT, E. muris subsp. eauclairensis Wisconsin. Numbers inside parentheses indicate the copy number of the gene; or else, only a single copy exists. +, genes present; -, homolog of the gene not identified based on Blast searches.
²In addition to Etf-2 (ECH_0261, 264 aa), E. chaffeensis encodes six paralogs of Etf-2 with protein sizes range from 190 ~ 350 AA (ECH_0243, 293 aa; ECH_0246, 285 aa; ECH_0247, 316 aa; ECH_0253, 189 aa; ECH_0255, 352 aa; and ECH_0257, 226 aa). However, only low homologies (26 ~ 32% AA sequence identity) to E. chaffeensis Etf-2 were identified in other Ehrlichia spp. (indicated by ±)
³Type I Secretion System is consisting of an outer membrane channel protein TolC, a membrane fusion protein HlyD, and an ATPase HlyB. All are present in these Ehrlichia spp
⁴Both twin-arginine translocase subunits TatA and TatC were identified in all Ehrlichia spp
⁵Tblastn search indicates that that the homolog of E. chaffeensis TRP120 in E. muris subsp. eauclairensis Wisconsin is split into two pseudogenes (EMUCRT_0995 and EMUCRT_0731) present in two separate contigs (NZ_LANU01000002 and NZ_LANU01000003) of the incomplete genome sequences
⁶Gene encoding CtrA protein was identified in E. muris subsp. muris AS145 genome. However, cckA gene is annotated as a pseudogene due to an internal deletion, causing frameshift at 1,123 bp

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