A chimeric disposition of the elongation factor genes in Rickettsia prowazekii

Syvänen, Ann‐Christine; Amiri, Haleh; Jamal, Asfar; Andersson, Siv G. E.; Kurland, C. G.

doi:10.1128/jb.178.21.6192-6199.1996

Cited by 27 publications

(25 citation statements)

References 64 publications

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“…Most other mitochondrial genomes appear to have lost all traces of the gene order of the putative bacterial ancestor. In effect, the gene order of the R. prowazekii genome is intermediate between that of R. americana and the more representative genomes of mitochondria (14,171). Thus, ancestral sequence motifs for genes encoding translation and transcription components are recognizable in R. prowazekii.…”

Section: Information Processesmentioning

confidence: 87%

“…In addition, the correlate is observed. Thus, the highly conserved operons for rRNA, proteins of the translation apparatus, and some metabolic enzymes are either gone from the Rickettsia genome or are retained in scrambled form (7,19,21,171). Such depredations are even more in evidence in the genomes of mitochondria.…”

Section: Genome Degradationmentioning

confidence: 94%

“…However, these gene orders are slightly scrambled (Fig. 9A), presumably as a result of intrachromosomal recombination within a genome that originally was arranged as in some modern bacteria (19,171).…”

Section: Information Processesmentioning

confidence: 99%

“…In the reduced genomes of Rickettsia, gene duplications common to other bacteria such as multiple rRNA operons and duplicated elongation factor Tu genes are missing (21,171). These, along with short repeat sequences that are common in free-living bacteria, seem to have been consumed by intrachromosomal recombination in the genome of Rickettsia (20).…”

Section: Genome Degradationmentioning

confidence: 99%

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Origin and Evolution of the Mitochondrial Proteome

Kurland

Andersson

2000

Microbiol Mol Biol Rev

362

272

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SUMMARY The endosymbiotic theory for the origin of mitochondria requires substantial modification. The three identifiable ancestral sources to the proteome of mitochondria are proteins descended from the ancestral α-proteobacteria symbiont, proteins with no homology to bacterial orthologs, and diverse proteins with bacterial affinities not derived from α-proteobacteria. Random mutations in the form of deletions large and small seem to have eliminated nonessential genes from the endosymbiont-mitochondrial genome lineages. This process, together with the transfer of genes from the endosymbiont-mitochondrial genome to nuclei, has led to a marked reduction in the size of mitochondrial genomes. All proteins of bacterial descent that are encoded by nuclear genes were probably transferred by the same mechanism, involving the disintegration of mitochondria or bacteria by the intracellular membranous vacuoles of cells to release nucleic acid fragments that transform the nuclear genome. This ongoing process has intermittently introduced bacterial genes to nuclear genomes. The genomes of the last common ancestor of all organisms, in particular of mitochondria, encoded cytochrome oxidase homologues. There are no phylogenetic indications either in the mitochondrial proteome or in the nuclear genomes that the initial or subsequent function of the ancestor to the mitochondria was anaerobic. In contrast, there are indications that relatively advanced eukaryotes adapted to anaerobiosis by dismantling their mitochondria and refitting them as hydrogenosomes. Accordingly, a continuous history of aerobic respiration seems to have been the fate of most mitochondrial lineages. The initial phases of this history may have involved aerobic respiration by the symbiont functioning as a scavenger of toxic oxygen. The transition to mitochondria capable of active ATP export to the host cell seems to have required recruitment of eukaryotic ATP transport proteins from the nucleus. The identity of the ancestral host of the α-proteobacterial endosymbiont is unclear, but there is no indication that it was an autotroph. There are no indications of a specific α-proteobacterial origin to genes for glycolysis. In the absence of data to the contrary, it is assumed that the ancestral host cell was a heterotroph.

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Section: Information Processesmentioning

confidence: 87%

Section: Genome Degradationmentioning

confidence: 94%

Section: Information Processesmentioning

confidence: 99%

Section: Genome Degradationmentioning

confidence: 99%

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Origin and Evolution of the Mitochondrial Proteome

Kurland

Andersson

2000

Microbiol Mol Biol Rev

362

272

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“…The tuf genes encoding EF-Tu are present in various copy numbers per bacterial genome. Most gram-negative bacteria contain two tuf genes (5,15,19,39,41,43). As found in Escherichia coli, the two genes, while being almost identical in sequence, are located in different parts of the bacterial chromosome (15,20,41).…”

mentioning

confidence: 99%

Evidence for Horizontal Gene Transfer in Evolution of Elongation Factor Tu in Enterococci

Boissinot

Huletsky

et al. 2000

J Bacteriol

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The elongation factor Tu, encoded by tuf genes, is a GTP binding protein that plays a central role in protein synthesis. One to three tuf genes per genome are present, depending on the bacterial species. Most low-G؉C-content gram-positive bacteria carry only one tuf gene. We have designed degenerate PCR primers derived from consensus sequences of the tuf gene to amplify partial tuf sequences from 17 enterococcal species and other phylogenetically related species. The amplified DNA fragments were sequenced either by direct sequencing or by sequencing cloned inserts containing putative amplicons. Two different tuf genes (tufA and tufB) were found in 11 enterococcal species, including Enterococcus avium, Enterococcus casseliflavus, Enterococcus dispar, Enterococcus durans, Enterococcus faecium, Enterococcus gallinarum, Enterococcus hirae, Enterococcus malodoratus, Enterococcus mundtii, Enterococcus pseudoavium, and Enterococcus raffinosus. For the other six enterococcal species (Enterococcus cecorum, Enterococcus columbae, Enterococcus faecalis, Enterococcus sulfureus, Enterococcus saccharolyticus, and Enterococcus solitarius), only the tufA gene was present. Based on 16S rRNA gene sequence analysis, the 11 species having two tuf genes all have a common ancestor, while the six species having only one copy diverged from the enterococcal lineage before that common ancestor. The presence of one or two copies of the tuf gene in enterococci was confirmed by Southern hybridization. Phylogenetic analysis of tuf sequences demonstrated that the enterococcal tufA gene branches with the Bacillus, Listeria, and Staphylococcus genera, while the enterococcal tufB gene clusters with the genera Streptococcus and Lactococcus. Primary structure analysis showed that four amino acid residues encoded within the sequenced regions are conserved and unique to the enterococcal tufB genes and the tuf genes of streptococci and Lactococcus lactis. The data suggest that an ancestral streptococcus or a streptococcus-related species may have horizontally transferred a tuf gene to the common ancestor of the 11 enterococcal species which now carry two tuf genes.

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Featured Organism: Reductive evolution in bacteria: Buchnera sp., Rickettsia prowazekii and Mycobacterium leprae

Wixon¹

2001

Comp Funct Genom

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Obligate intracellular bacteria commonly have much reduced genome sizes compared to their nearest free-living relatives. One reason for this is reductive evolution: the loss of genes rendered non-essential due to the intracellular habitat. This can occur because of the presence of orthologous genes in the host, combined with the ability of the bacteria to import the protein or metabolite products of the host genes. In this article we take a look at three such bacteria whose genomes have been fully sequenced. Buchnera is an endosymbiont of the pea aphid, Acyrthosiphon pisum, the relationship between these two organisms being so essential that neither can reproduce in the absence of the other. Rickettsia prowazekii is the causative agent of louse-borne typhus in humans and Mycobacterium leprae infection of humans leads to leprosy. Both of these human pathogens have fastidious growth requirements, which has made them very difficult to study.

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A chimeric disposition of the elongation factor genes in Rickettsia prowazekii

Cited by 27 publications

References 64 publications

Origin and Evolution of the Mitochondrial Proteome

Origin and Evolution of the Mitochondrial Proteome

Evidence for Horizontal Gene Transfer in Evolution of Elongation Factor Tu in Enterococci

Featured Organism: Reductive evolution in bacteria: Buchnera sp., Rickettsia prowazekii and Mycobacterium leprae

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