Phosphorylation at serines 216 and 221 is important for Drosophila HeT-A Gag protein stability.
Telomeres from Drosophila appear to be very different from those of other organisms - in size and the mechanism of their maintenance. In the absence of the enzyme telomerase, Drosophila telomeres are maintained by retrotransposition of three elements, HeT-A, TART, and TAHRE, but details of their transposition mechanisms are not known. Here we characterized some biochemical characteristics of the HeT-A Gag protein encoded by the HeT-A element to understand this mechanism. The HeT-A Gag protein when overexpressed in S2 cells was localized to the nucleus but was resistant to high salt, detergents and nuclease extraction treatments. Analysis of the HeT-A Gag protein by tandem mass spectrophotometry revealed that serines 216 and 221 are phosphorylated. Substituting these serines with alanine or aspartic acid by site-directed mutagenesis did not result in any changes in HeT-A Gag translocation across the nucleus, suggesting that phosphorylation of these sites is not associated with HeT-A Gag translocation, but time course experiments showed that these phosphorylation sites are important for Gag-protein stability.
Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, United States of America.
Sukhdev S
SS
Brar
Robert M
RM
Petrovich
Jason G
JG
Williams
James M
JM
Mason
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000409:Alanine / Q000235:genetics / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D010766:Phosphorylation / Q000502:physiology; D055550:Protein Stability; D018626:Retroelements / Q000502:physiology*; D053719:Tandem Mass Spectrometry
D029721:Drosophila Proteins; D015683:Gene Products, gag; D018626:Retroelements; D001224:Aspartic Acid; D000409:Alanine