Fructose-1,6-bisphosphate aldolases in amitochondriate protists constitute a single protein subfamily with eubacterial relationships.
Sequences of putative fructose-1,6-bisphospate aldolases (FBA) in five amitochondriate unicellular eukaryotes, the diplomonads Giardia intestinalis (published earlier) and Spironucleus barkhanus, the pelobiont Mastigamoeba balamuthi,the entamoebid Entamoeba histolytica, and the parabasalid Trichomonas vaginalis all belong to Class II of FBAs and are highly similar to each other (>48% amino acid identity). The five protist sequences, however, do not form a monophyletic group. Diplomonad FBAs share a most recent common ancestor, while FBAs of the three other protist species are part of a lineage that also includes sequences from a few eubacteria (Clostridium difficile, Treponema pallidum, Chlorobium tepidum). Both clades are part of the Type B of Class II aldolases, a complex that contains at least three additional lineages (subgroups) of enzymes. Type B enzymes are distant from Type A Class II aldolases, which consists of a number of bacterial and fungal enzymes and also contains the cytosolic FBA of Euglena gracilis. Class II aldolases are not homologous to Class I enzymes, to which animal and plant enzymes belong. The results indicate that amitochondriate protists acquired their FBAs from separate and different sources, involving lateral gene transfer from eubacteria, than did all other eukaryotes studied so far and underscore the complex composition of the glycolytic machinery in unicellular eukaryotes.
Sánchez
Lidya
L
The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA. sanchel@mail.rockefeller.edu
Horner
David
D
Moore
Dorothy
D
Henze
Katrin
K
Embley
T
T
Müller
Miklós
M
D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D016828:Diplomonadida / Q000201:enzymology / Q000235:genetics; D004748:Entamoeba histolytica / Q000201:enzymology / Q000235:genetics; D056890:Eukaryota / Q000201:enzymology / Q000235:genetics*; D005634:Fructose-Bisphosphate Aldolase / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014246:Trichomonas vaginalis / Q000201:enzymology / Q000235:genetics
D018076:DNA, Complementary; D016054:DNA, Protozoan; D005634:Fructose-Bisphosphate Aldolase