title: Iron-dependent hydrogenases of Entamoeba histolytica and Giardia lamblia: activity of the recombinant entamoebic enzyme and evidence for lateral gene transfer.
abstract: Entamoeba histolytica and Spironucleus barkhanus have genes that encode short iron-dependent hydrogenases (Fe-hydrogenases), even though these protists lack hydrogenosomes. To understand better the biochemistry of the protist Fe-hydrogenases, we prepared a recombinant E. histolytica short Fe-hydrogenase and measured its activity in vitro. A Giardia lamblia gene encoding a short Fe-hydrogenase was identified from shotgun genomic sequences, and RT-PCR showed that cultured entamoebas and giardias transcribe short Fe-hydrogenase mRNAs. A second E. histolytica gene, which encoded a long Fe-hydrogenase, was identified from shotgun genomic sequences. Phylogenetic analyses suggested that the short Fe-hydrogenase genes of entamoeba and diplomonads share a common ancestor, while the long Fe-hydrogenase gene of entamoeba appears to have been laterally transferred from a bacterium. These results are discussed in the context of competing ideas for the origins of genes encoding fermentation enzymes of these protists.
authors.affiliation: Department of Immunology and Infectious Diseases, Harvard School of Public Health, 665 Huntington Ave., Boston, Massachusetts, USA.
authors.forename: Julie E J
authors.initials: JE
authors.lastname: Nixon
authors.forename: Jessica
authors.initials: J
authors.lastname: Field
authors.forename: Andrew G
authors.initials: AG
authors.lastname: McArthur
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Sogin
authors.forename: Nigel
authors.initials: N
authors.lastname: Yarlett
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Loftus
authors.forename: John
authors.initials: J
authors.lastname: Samuelson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004748:Entamoeba histolytica / Q000201:enzymology* / Q000235:genetics; D022761:Gene Transfer, Horizontal; D016829:Giardia lamblia / Q000201:enzymology* / Q000235:genetics; D006864:Hydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D012333:RNA, Messenger; D011994:Recombinant Proteins; D007501:Iron; D006864:Hydrogenase