Complete Genome Sequence ofRickettsia typhiand Comparison with Sequences of Other Rickettsiae

Abstract

Rickettsia typhi, the causative agent of murine typhus, is an obligate intracellular bacterium with a life cycle involving both vertebrate and invertebrate hosts. Here we present the complete genome sequence of R. typhi (1,111,496 bp) and compare it to the two published rickettsial genome sequences: R. prowazekii and R. conorii. We identified 877 genes in R. typhi encoding 3 rRNAs, 33 tRNAs, 3 noncoding RNAs, and 838 proteins, 3 of which are frameshifts. In addition, we discovered more than 40 pseudogenes, including the entire cytochrome c oxidase system. The three rickettsial genomes share 775 genes: 23 are found only in R. prowazekii and R. typhi, 15 are found only in R. conorii and R. typhi, and 24 are unique to R. typhi. Although most of the genes are colinear, there is a 35-kb inversion in gene order, which is close to the replication terminus, in R. typhi, compared to R. prowazekii and R. conorii. In addition, we found a 124-kb R. typhi-specific inversion, starting 19 kb from the origin of replication, compared to R. prowazekii and R. conorii. Inversions in this region are also seen in the unpublished genome sequences of R. sibirica and R. rickettsii, indicating that this region is a hot spot for rearrangements. Genome comparisons also revealed a 12-kb insertion in the R. prowazekii genome, relative to R. typhi and R. conorii, which appears to have occurred after the typhus (R. prowazekii and R. typhi) and spotted fever (R. conorii) groups diverged. The three-way comparison allowed further in silico analysis of the SpoT split genes, leading us to propose that the stringent response system is still functional in these rickettsiae.

Rickettsia and Rickettsial Diseases

“…The mechanism of lysis of the phagosomal membrane and the host cell membrane has been hypothesized to be mediated by a phospholipase enzyme (Radulovic et al, 1999;Renesto et al, 2003). The genomic sequences of Rickettsia have revealed four proteins with potential membranolytic activities: patatin B1 precursor (pat-1 gene), hemolysin A (tlyA), hemolysin C (tlyC), and phospholipase D (pld) (Andersson et al, 1998;Ogata et al, 2001;McLeod et al, 2004). TlyC has been demonstrated to have hemolytic activity, (Radulovic et al, 1999) and can mediate escape by S. enterica serovar Typhimurium from phagosomes (Whitworth et al, 2005).…”

Lateral gene transfer between obligate intracellular bacteria: Evidence from the Rickettsia massiliae genome

“…In contrast, homologs are present in the R. massiliae (RMA_p01) and R. felis (pRF19) plasmids and in the R. bellii (RBE_1035) and the R. prowazekii (pseudogene between RP708 and RP709) genomes. The R. prowazekii U pseudogene is located in a 12-kb region specific to R. prowazekii (McLeod et al 2004), which also includes several transposase (RP710 and RP715) and recombinase pseudogenes (RP711) that are uniquely found on both the R. felis and R. massiliae plasmids (Supplemental Fig. S9).…”

“…To date, 10 complete Rickettsia genome sequences have been deposited in public databases. They include the genomes of two R. bellii strains (GenBank AARC00000000; Ogata et al 2006), two sequences from the TG rickettsiae (R. prowazekii [Andersson et al 1998] and R. typhi [McLeod et al 2004]), five sequences from the SFG group (R. conorii [Ogata et al 2001], Rickettsia sibirica [Malek et al 2004], R. rickettsii [GenBank AADJ00000000], Rickettsia felis [Ogata et al 2005] and Rickettsia akarii [GenBank AAFE00000000]), and the sequence of Rickettsia canadensis (Eremeeva et al 2005) for which the phylogenetic position is unclear. Here, we report the sequencing and the primary analysis of the genome of R. massiliae strain MTU5 isolated from the R. turanicus tick collected on horses in Camargues, France.…”

The effects of, and interactions between, Cardinium and Wolbachia in the doubly infected spider mite Bryobia sarothamni

“…Presence of Cardinium was detected using PCR amplification of a part of the 16S rDNA and gyrB. Wsp was amplified using the primers wsp-81F and wsp-691R , and gltA using the primers gltA-F 5 0 -GAYCATGARCAR AAYGCTTCTAC-3 0 and gltA-R 5 0 -CCHGARTAAAAAT CAACRTTDGG-3 0 , designed from available Wolbachia and Rickettsia genome sequences (Andersson et al, 1998;McLeod et al, 2004;Wu et al, 2004), and tested on isolates representative of Wolbachia supergroups A and B. Cardinium 16S rDNA was amplified using the primers CLOf and CLOr1 (Weeks et al, 2003). GyrB was amplified using primers from Groot and Breeuwer (2006).…”