Document Detail

Phylogenetic affinities between eukaryotic cells and a thermophilic mycoplasma.
MedLine Citation:
PMID:  656568     Owner:  NLM     Status:  MEDLINE    
Thermoplasma acidophilum, a thermophilic mycoplasma, has several unusual features suggesting a possible relationship to eukaryotic cells. One feature is a histone-like protein that is associated with the DNA, condensing it into subunits similar to those in eukaryotic chromatin. A second feature is an association of cytoplasmic proteins that resembles eukaryotic actin and myosin. These two components are widely distributed in different groups of eukaryotic cells, but are typically lacking in prokaryotic cells. Furthermore, T. acidophilum lacks cytochromes and respires by enzymes that apparently are not coupled to oxidative phosphorylation. This primitive type of respiration resembles that of microbodies, another feature which is represented in the cytoplasm of all groups of eukaryotic cells. Furthermore, since T. acidophilum lacks a cell wall and appears to have a primitive correlate of endocytosis, it would appear to be mechanically capable of acquiring a symbiotic mitochondrion. Thus, our observations are consistent with the symbiotic hypothesis for the origin of eukaryotic cells. We suggest that an organism similar to T. acidophilum was the host cell for the original symbiosis, becoming the nucleus and cytoplasm of modern eukaryotic cells.
D G Searcy; D B Stein; G R Green
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Bio Systems     Volume:  10     ISSN:  0303-2647     ISO Abbreviation:  BioSystems     Publication Date:  1978 Apr 
Date Detail:
Created Date:  1978-08-28     Completed Date:  1978-08-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0430773     Medline TA:  Biosystems     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  19-28     Citation Subset:  IM; S    
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MeSH Terms
Bacterial Proteins
DNA, Bacterial / metabolism
Eukaryotic Cells*
Oxygen Consumption
Thermoplasma* / analysis,  metabolism
Reg. No./Substance:
0/Bacterial Proteins; 0/DNA, Bacterial; 0/Histones; 9013-26-7/Actomyosin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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