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Journal of Molecular Evolution

, Volume 48, Issue 6, pp 750–755 | Cite as

Primary Structure and Phylogenetic Relationships of a Malate Dehydrogenase Gene from Giardia lamblia

  • Andrew J.  Roger
  • Hilary G.  Morrison
  • Mitchell L.  Sogin

Abstract.

The lactate and malate dehydrogenases comprise a complex protein superfamily with multiple enzyme homologues found in eubacteria, archaebacteria, and eukaryotes. In this study we describe the sequence and phylogenetic relationships of a malate dehydrogenase (MDH) gene from the amitochondriate diplomonad protist, Giardia lamblia. Parsimony, distance, and maximum-likelihood analyses of the MDH protein family solidly position G. lamblia MDH within a eukaryote cytosolic MDH clade, to the exclusion of chloroplast, mitochondrial, and peroxisomal homologues. Furthermore, G. lamblia MDH is specifically related to a homologue from Trichomonas vaginalis. This MDH topology, together with published phylogenetic analyses of β-tubulin, chaperonin 60, valyl-tRNA synthetase, and EF-1α, suggests a sister-group relationship between diplomonads and parabasalids. Since these amitochondriate lineages contain genes encoding proteins which are characteristic of mitochondria and α-proteobacteria, their shared ancestry suggests that mitochondrial properties were lost in the common ancestor of both groups.

Key words:Giardia lamblia— Diplomonads — Malate dehydrogenase — Protein phylogeny — Amitochondriate protist 

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Copyright information

© Springer-Verlag New York Inc. 1999

Authors and Affiliations

  • Andrew J.  Roger
    • 1
  • Hilary G.  Morrison
    • 1
  • Mitchell L.  Sogin
    • 1
  1. 1.Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543-1015, USAUS

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