Phylogenetic affinities between eukaryotic cells and a thermophilic mycoplasma

Searcy, Dennis G.; Stein, Diana B.; Green, George R.

doi:10.1016/0303-2647(78)90024-2

Cited by 74 publications

(26 citation statements)

References 43 publications

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“…2). The existence of an actin-like molecule in archaebacteria was previously suggested by Searcy and coworkers, who reported that cytochalasin B inhibits the growth of the archaebacterium Thermoplusma acidophilum [26]. to the fl-tubulin yeast gene and different genomic digests of H .…”

Section: Indications For An Actin-like Sequence and For Actin-like Anmentioning

confidence: 76%

Antitumor drugs inhibit the growth of halophilic archaebacteria

et al. 1987

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Permeability mutants of Escherichia coli have been used to prescreen antitumor drugs. However, most compounds active against eucaryotic proteins have no effect on isofunctional proteins of eubacteria. In contrast, we show that growth of halophilic archaebacteria, procaryotes as distantly related to eubacteria as to eucaryotes, is inhibited by several drugs known to interact with tubulin, actomyosin and DNA topoisomerase I1 of eucaryotes. Actually, different types of evidence indicate the presence of analogous proteins in halophilic archaebacteria : (a) a yeast actin probe hybridizes with DNA restriction digests of Halobacterium halobium; (b) antibodies against tubulin and actin from chicken react in a crude extract of H. halohiurn with polypeptides having M , of 55000 and 80000, respectively; (c) the epipodophyllotoxin VP16, a eucaryotic DNA topoisomerase I1 inhibitor, induces DNA strand breaks with DNA-protein covalent linkage in H . halohiurn as in eucaryotes. Besides the evolutionary implications, these data indicate that halophilic archaebacteria can be used to prescreen antitumor drugs active on eucaryotic proteins.Antibiotics useful in cancer therapy include drugs whose primary target is DNA (alkylating agents, DNA intercalators, DNA binding agents) and drugs which interact with essential cellular proteins (tubulin, type I1 DNA topoisomerases). Procaryotic microorganisms, especially the eubacterium Escherichia coli, have been useful for prescreening a few antitumor drugs [l]. However, most antibiotics active against eucaryotic proteins have no effect on isofunctional proteins in eubacteria; therefore, these procaryotes are only suitable to search for drugs which interact directly with DNA. Unfortunately, such compounds are not only carcinostatic but also carcinogenic [l]. Archaebacteria constitute a group of procaryotes as distantly related to classical bacteria (eubacteria) as to eucaryotes [2]. Growth of some archaebacteria is inhibited by anisomycin and aphidicolin, two antibiotics which were hitherto known to be specific for eukaryotic cells [3, 41. Recently, we have shown that growth of halophilic archaebacteria (halobacteria) is inhibited by the epipodophyllotoxin etoposide (VP16) [5], an inhibitor of eucaryotic type I1 DNA topoisomerases which is widely used in tumor therapy [6]. This prompted us to check whether halobacteria were sensitive to other antitumor drugs. Halobacteria are particularly suitable for in vivo studies with Abbreviations. m-AMSA, 4-(9-acridinylamino)methane sulfonm-aniside; 2-Me-90H-E, 2-methyl-9-hydroxyellipticinium; NaCl/Cit, 0.15 M NaCI, 0.015 M trisodium citrate, pH 7.0; VM26, 4 -demethylepipodophyllotoxin thenylidene fl-D-ghcoside; VP16, demethylepipodophyllotoxin ethylidene fl-D-glucoside; ID,o, drug concentration inhibiting cell growth by 50%.

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Section: Indications For An Actin-like Sequence and For Actin-like Anmentioning

confidence: 76%

Antitumor drugs inhibit the growth of halophilic archaebacteria

et al. 1987

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“…Organic acid syntrophy (Fig 4) This hypothesis was the first to be suggested, and was modeled on the modern relationship of the cytoplasm and mitochondria [31][32][33]. The host cell fermented organic matter such as glucose to organic acids such as pyruvate and lactate.…”

Section: Mitochondrial Origin From a Mutualistic Symbiosismentioning

confidence: 99%

Metabolic integration during the evolutionary origin of mitochondria

Searcy

2003

Cell Res

115

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Although mitochondria provide eukaryotic cells with certain metabolic advantages, in other ways they may be disadvantageous. For example, mitochondria produce reactive oxygen species that damage both nucleocytoplasm and mitochondria, resulting in mutations, diseases, and aging. The relationship of mitochondria to the cytoplasm is best understood in the context of evolutionary history. Although it is clear that mitochondria evolved from symbiotic bacteria, the exact nature of the initial symbiosis is a matter of continuing debate. The exchange of nutrients between host and symbiont may have differed from that between the cytoplasm and mitochondria in modern cells. Speculations about the initial relationships include the following.(1) The pre-mitochondrion may have been an invasive, parasitic bacterium. The host did not benefit. (2) The relationship was a nutritional syntrophy based upon transfer of organic acids from host to symbiont. (3) The relationship was a syntrophy based upon H2 transfer from symbiont to host, where the host was a methanogen. (4) There was a syntrophy based upon reciprocal exchange of sulfur compounds. The last conjecture receives support from our detection in eukaryotic cells of substantial H2S-oxidizing activity in mitochondria, and sulfur-reducing activity in the cytoplasm.

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“…As does its extant descendant, the ancient archaebacterium survived acid-hydrolysis environmental conditions by nucleosome-style histone-like protein coating of its DNA (14) and actin-like stress-protein synthesis (15). The wall-less archaebacterium was remarkably pleiomorphic; it tended into tight physical association with globules of elemental sulfur by use of its rudimentary cytoskeletal system (16). The second member of the consortium, an obligate anaerobe, required for growth the highly reduced conditions provided by sulfur and sulfate reduction to hydrogen sulfide.…”

Section: Two Domains Not Threementioning

confidence: 99%

“…acidophilum in pure culture attach to suspended elemental sulfur. When sulfur is available, they generate hydrogen sulfide (16). Although severely hindered by ambient oxygen, they are (28).…”

Section: The ''Thiodendron'' Stagementioning

confidence: 99%

The chimeric eukaryote: Origin of the nucleus from the karyomastigont in amitochondriate protists

Margulis

Dolan

Guerrero

2000

Proc. Natl. Acad. Sci. U.S.A.

177

107

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We present a testable model for the origin of the nucleus, the membrane-bounded organelle that defines eukaryotes. A chimeric cell evolved via symbiogenesis by syntrophic merger between an archaebacterium and a eubacterium. The archaebacterium, a thermoacidophil resembling extant Thermoplasma, generated hydrogen sulfide to protect the eubacterium, a heterotrophic swimmer comparable to Spirochaeta or Hollandina that oxidized sulfide to sulfur. Selection pressure for speed swimming and oxygen avoidance led to an ancient analogue of the extant cosmopolitan bacterial consortium ''Thiodendron latens.'' By eubacterial-archaebacterial genetic integration, the chimera, an amitochondriate heterotroph, evolved. This ''earliest branching protist'' that formed by permanent DNA recombination generated the nucleus as a component of the karyomastigont, an intracellular complex that assured genetic continuity of the former symbionts. The karyomastigont organellar system, common in extant amitochondriate protists as well as in presumed mitochondriate ancestors, minimally consists of a single nucleus, a single kinetosome and their protein connector. As predecessor of standard mitosis, the karyomastigont preceded free (unattached) nuclei. The nucleus evolved in karyomastigont ancestors by detachment at least five times (archamoebae, calonymphids, chlorophyte green algae, ciliates, foraminifera). This specific model of syntrophic chimeric fusion can be proved by sequence comparison of functional domains of motility proteins isolated from candidate taxa.Archaeprotists ͉ spirochetes ͉ sulfur syntrophy ͉ Thiodendron ͉ trichomonad Two Domains, Not Three

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Phylogenetic affinities between eukaryotic cells and a thermophilic mycoplasma

Cited by 74 publications

References 43 publications

Antitumor drugs inhibit the growth of halophilic archaebacteria

Antitumor drugs inhibit the growth of halophilic archaebacteria

Metabolic integration during the evolutionary origin of mitochondria

The chimeric eukaryote: Origin of the nucleus from the karyomastigont in amitochondriate protists

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