Functional conservation of subfamilies of putative UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferases in Drosophila, Caenorhabditis elegans, and mammals. One subfamily composed of l(2)35Aa is essential in Drosophila.
The completed fruit fly genome was found to contain up to 15 putative UDP-N-acetyl-alpha-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase (GalNAc-transferase) genes. Phylogenetic analysis of the putative catalytic domains of the large GalNAc-transferase enzyme families of Drosophila melanogaster (13 available), Caenorhabditis elegans (9 genes), and mammals (12 genes) indicated that distinct subfamilies of orthologous genes are conserved in each species. In support of this hypothesis, we provide evidence that distinctive functional properties of Drosophila and human GalNAc-transferase isoforms were exhibited by evolutionarily conserved members of two subfamilies (dGalNAc-T1 (l(2)35Aa) and GalNAc-T11; dGalNAc-T2 (CG6394) and GalNAc-T7). dGalNAc-T1 and novel human GalNAc-T11 were shown to encode functional GalNAc-transferases with the same polypeptide acceptor substrate specificity, and dGalNAc-T2 was shown to encode a GalNAc-transferase with similar GalNAc glycopeptide substrate specificity as GalNAc-T7. Previous data suggested that the putative GalNAc-transferase encoded by l(2)35Aa had a lethal phenotype (Flores, C., and Engels, W. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 2964-2969), and this was substantiated by sequencing of three lethal alleles l(2)35Aa(HG8), l(2)35Aa(SF12), and l(2)35Aa(SF32). The finding that subfamilies of GalNAc-transferases with distinct catalytic functions are evolutionarily conserved stresses that GalNAc-transferase isoforms may serve unique biological functions rather than providing functional redundancy, and this is further supported by the lethal phenotype of l(2)35Aa.
Schwientek
Tilo
T
School of Dentistry, University of Copenhagen, Nørre Alle 20, 2200 Copenhagen N, Denmark. akd88@uni-koeln.de
Bennett
Eric P
EP
Flores
Carlos
C
Thacker
John
J
Hollmann
Martin
M
Reis
Celso A
CA
Behrens
Jane
J
Mandel
Ulla
U
Keck
Birgit
B
Schäfer
Mireille A
MA
Haselmann
Kim
K
Zubarev
Roman
R
Roepstorff
Peter
P
Burchell
Joy M
JM
Taylor-Papadimitriou
Joyce
J
Hollingsworth
Michael A
MA
Clausen
Henrik
H
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D017173:Caenorhabditis elegans / Q000378:metabolism*; D020134:Catalytic Domain; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004331:Drosophila melanogaster / Q000378:metabolism*; D019143:Evolution, Molecular; D005260:Female; D016678:Genome; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D017350:N-Acetylgalactosaminyltransferases / Q000737:chemistry* / Q000378:metabolism*; D010053:Ovary / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010641:Phenotype; D010802:Phylogeny; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014018:Tissue Distribution; D000097763:Polypeptide N-acetylgalactosaminyltransferase
D017350:N-Acetylgalactosaminyltransferases; D010455:Peptides; D020033:Protein Isoforms; D000097763:Polypeptide N-acetylgalactosaminyltransferase