Sorbitol dehydrogenase of Drosophila. Gene, protein, and expression data show a two-gene system.
The Drosophila melanogaster sorbitol dehydrogenase (SDH) is characterized as a two-enzyme system of the medium chain dehydrogenase/reductase family (MDR). The SDH-1 enzyme has an enzymology with Km and kcat values an order of magnitude higher than those for the human enzyme but with a similar kcat/Km ratio. It is a tetramer with identical subunits of approximately 38 kDa. At the genomic level, two genes, Sdh-1 and Sdh-2, have a single transcriptional start site and no functional TATA box. Expression is greater in larvae and adults than in pupae, where it is very low. At all three stages, Sdh-1 constitutes the major transcript. Sdh-1 and Sdh-2 genes were located at positions 84E-F and 86D in polytene chromosomes. The deduced amino acid sequences of the two genes show 90% residue identity. Evaluation of the sequence and modeling of the structure toward that of class I alcohol dehydrogenase (ADH) show altered loop and gap arrangements as in mammalian SDH and establishes that SDH, despite gene multiplicity and larger variability than the "constant" ADH of class III, is an enzyme conserved over wide ranges.
Luque
T
T
Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645, E-08071 Barcelona, Spain.
Hjelmqvist
L
L
Marfany
G
G
Danielsson
O
O
El-Ahmad
M
M
Persson
B
B
Jörnvall
H
H
González-Duarte
R
R
D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D020134:Catalytic Domain; D002875:Chromosomes / Q000235:genetics / Q000648:ultrastructure; D016384:Consensus Sequence; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics*; D019143:Evolution, Molecular; D005091:Exons; D017344:Genes, Insect; D006801:Humans; D017403:In Situ Hybridization; D007438:Introns; D007064:L-Iditol 2-Dehydrogenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D017433:Protein Structure, Secondary; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D000426:Alcohol Dehydrogenase; D007064:L-Iditol 2-Dehydrogenase