Functional divergence of six isoforms of antifungal peptide Drosomycin in Drosophila melanogaster.
Drosomycin (Drs) gene encodes a 44-residue inducible antifungal peptide, Drosomycin, in Drosophila melanogaster. Six genes, Drs-lC, Drs-lD, Drs-lE, Drs-lF, Drs-lG and Drs-lI, show homology to the Drs form in a multigene family on the 3rd chromosome of D. melanogaster. It is the first experimental demonstration that the six members in the Drs family act as functional genes. To further delineate the functional divergence of these six members, their cDNA sequences were cloned respectively into the pET-3C vector and expressed in the E. coli. The antifungal activity of the expression products was assayed using the Cerletti's method. The results showed a difference among the six isoforms in antifungal activity against the tested fungal strains: in which Drs was most effective and showed antifungal activity to all seven fungal strains, whereas isoform Drs-lC was effective to six strains, Drs-lD was effective to five strains, Drs-lG was effective to four strains, and Drs-lE and Drs-lF were effective to only three strains. Drs-lI had no activity against any tested fungal strains. By comparing the variable residue sites of these six isoforms to that of Drosomycin in the three-dimensional structure, we suggested that the reduction in the antifungal activity was due to the variable residues that were not in the alpha-helix. In addition, two inserted residues (RV) in Drs-lI may affect the dimensional structure and resulted in a functional change. These results may explain the evolution of the Drosomycin multigene family and its functional divergence.
Yang
Wan-Ying
WY
Department of Sericulture Science, College of Animal Science, South China Agricultural University, 510642, Guangzhou, PR China.
Wen
Shuo-Yang
SY
Huang
Ya-Dong
YD
Ye
Ming-Qiang
MQ
Deng
Xiao-Juan
XJ
Han
Dong
D
Xia
Qin-You
QY
Cao
Yang
Y
D000595:Amino Acid Sequence; D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D029721:Drosophila Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D004331:Drosophila melanogaster / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D016133:Polymerase Chain Reaction; D017510:Protein Folding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D016415:Sequence Alignment
D000935:Antifungal Agents; D023181:Antimicrobial Cationic Peptides; D029721:Drosophila Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; C091227:DRS protein, Drosophila