title: Spt5 and spt6 are associated with active transcription and have characteristics of general elongation factors in D. melanogaster.
abstract: The Spt4, Spt5, and Spt6 proteins are conserved throughout eukaryotes and are believed to play critical and related roles in transcription. They have a positive role in transcription elongation in Saccharomyces cerevisiae and in the activation of transcription by the HIV Tat protein in human cells. In contrast, a complex of Spt4 and Spt5 is required in vitro for the inhibition of RNA polymerase II (Pol II) elongation by the drug DRB, suggesting also a negative role in vivo. To learn more about the function of the Spt4/Spt5 complex and Spt6 in vivo, we have identified Drosophila homologs of Spt5 and Spt6 and characterized their localization on Drosophila polytene chromosomes. We find that Spt5 and Spt6 localize extensively with the phosphorylated, actively elongating form of Pol II, to transcriptionally active sites during salivary gland development and upon heat shock. Furthermore, Spt5 and Spt6 do not colocalize widely with the unphosphorylated, nonelongating form of Pol II. These results strongly suggest that Spt5 and Spt6 play closely related roles associated with active transcription in vivo.
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Kaplan
authors.forename: J R
authors.initials: JR
authors.lastname: Morris
authors.forename: C
authors.initials: C
authors.lastname: Wu
authors.forename: F
authors.initials: F
authors.lastname: Winston
mesh_terms: D000818:Animals; D002868:Chromosomal Proteins, Non-Histone; D002875:Chromosomes / Q000378:metabolism; D056906:Cyclin T; D016213:Cyclins / Q000378:metabolism; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D004625:Embryo, Nonmammalian; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005967:Glue Proteins, Drosophila / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D056488:Histone Chaperones; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017421:Sequence Analysis; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors
chemical_list: C503684:CCNT1 protein, human; D002868:Chromosomal Proteins, Non-Histone; C503687:CycT protein, Drosophila; D056906:Cyclin T; D016213:Cyclins; D029721:Drosophila Proteins; D005656:Fungal Proteins; D005967:Glue Proteins, Drosophila; D056488:Histone Chaperones; D019476:Insect Proteins; D009687:Nuclear Proteins; D010445:Peptide Elongation Factors; C065456:SPT6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035602:Transcriptional Elongation Factors; C069940:SPT5 transcriptional elongation factor; D012319:RNA Polymerase II