title: Glutamine synthetase gene evolution: a good molecular clock.
abstract: Glutamine synthetase (EC 6.3.1.2) gene evolution in various animals, plants, and bacteria was evaluated by a general stationary Markov model. The evolutionary process proved to be unexpectedly regular even for a time span as long as that between the divergence of prokaryotes from eukaryotes. This enabled us to draw phylogenetic trees for species whose phylogeny cannot be easily reconstructed from the fossil record. Our calculation of the times of divergence of the various organelle-specific enzymes led us to hypothesize that the pea and bean chloroplast genes for these enzymes originated from the duplication of nuclear genes as a result of the different metabolic needs of the various species. Our data indicate that the duplication of plastid glutamine synthetase genes occurred long after the endosymbiotic events that produced the organelles themselves.
authors.affiliation: Dipartimento di Biochimica e Biologia Molecolare, Universitá di Bari, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Pesole
authors.forename: M P
authors.initials: MP
authors.lastname: Bozzetti
authors.forename: C
authors.initials: C
authors.lastname: Lanave
authors.forename: G
authors.initials: G
authors.lastname: Preparata
authors.forename: C
authors.initials: C
authors.lastname: Saccone
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000201:enzymology / Q000235:genetics; D005075:Biological Evolution; D005796:Genes; D014644:Genetic Variation; D005974:Glutamate-Ammonia Ligase / Q000235:genetics*; D006801:Humans; D010944:Plants / Q000201:enzymology / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D005974:Glutamate-Ammonia Ligase