The Knickkopf DOMON domain is essential for cuticle differentiation in Drosophila melanogaster.
The dopamine monoxygenase N-terminal (DOMON) domain is found in extracellular proteins across several eukaryotic and prokaryotic taxa. It has been proposed that this domain binds to heme or sugar moieties. Here, we have analyzed the role of four highly conserved amino acids in the DOMON domain of the Drosophila melanogaster Knickkopf protein that is inserted into the apical plasma membrane and assists extracellular chitin organization. In principal, we generated Knickkopf versions with exchanged residues tryptophan(299), methionine(333), arginine(401), or histidine(437), and scored for the ability of the respective engineered protein to normalize the knickkopf mutant phenotype. Our results confirm the absolute necessity of tryptophan(299), methionine(333), and histidine(437) for Knickkopf function and stability, the latter two being predicted to be critical for heme binding. In contrast, arginine(401) is required for full efficiency of Knickkopf activity. Taken together, our genetic data support the prediction of these residues to mediate the function of Knickkopf during cuticle differentiation in insects. Hence, the DOMON domain is apparently an essential factor contributing to the construction of polysaccharide-based extracellular matrices.
Genetik der Tiere, Interfaculty Institute for Cell Biology, Eberhard-Karls University of Tübingen, Tübingen, Germany.
Khaleelulla Saheb
KS
Shaik
Yiwen
Y
Wang
L
L
Aravind
Bernard
B
Moussian
D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D002686:Chitin / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism
D000596:Amino Acids; D029721:Drosophila Proteins; C506753:knk protein, Drosophila; D002686:Chitin
DOMON; Drosophila; chitin; cuticle; redox reaction