Evolution

Mixing and Matching, Maybe

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Science  17 May 2002:
Vol. 296, Issue 5571, pp. 1205
DOI: 10.1126/science.296.5571.1205d

The central position of ribosomal RNA (rRNA) in molecular phylogenetics has recently been reinforced, both by its demonstrated importance in translation and by the evolutionary proximity of nucleic acid machinery (mediating replication and transcription) in eukaryotic and archaeal lineages. Nevertheless, the heated discussion concerning metabolic enzymes has been stoked by the provision of new genome sequences. Now, Canback et al. suggest that the eukaryotic glycolytic enzymes cannot have been obtained en masse from the mitochondrial symbiont, because they do not cluster with the enzymes of α-proteobacteria. On the other hand, these protein trees and those of other metabolic pathways are not simply isomorphic with that of rRNA, which may in part be due to lateral gene transfer among the ancestors of extant α-proteobacteria and even between eukaryotic hosts and pathogenic bacteria. For a historical view of the continuing debate about the origin of the mitochondrion, see Martin et al.GJC

Proc. Natl. Acad. Sci. U.S.A.99, 6097 (2002); Biol. Chem.382, 1521 (2001).

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