Date of Award
Doctor of Philosophy
Biochemistry, Biophysics and Molecular Biology
Kristen M. Johansen
JIL-1 encodes a chromatin-associated tandem serine/threonine kinase in Drosophila melanogaster. JIL-1 predominantly associates with interbands on polytene chromosomes. It appears at higher levels on the X chromosome than on autosomes in males, and distributes about equally on all chromosomes in females. In addition, in males JIL-1 overlaps with the MSL (for male specific lethal) complex that specifically associates with the male X chromosome on which expression of most genes are upregulated.;We isolated JIL-1 mutants by inducing imprecise excision of an EP element inserted in JIL-1. We found that JIL-1 is required for viability of both females and males, but male viability is more sensitive to reduction of JIL-1 levels. Additionally, JIL-1 is required for embryogenesis, oogenesis and segment identity. Polytene chromosomes from JIL-1 mutant third instar larvae are shortened, coiled and lose their banding patterns, suggesting that JIL-1 plays a role in maintaining higher order chromatin structure. JIL-1 mutants show reduced levels of histone H3 serine10 (ser10) phosphorylation. The higher level of histone H3 ser10 phosphorylation on the male X chromosome is dependent upon JIL-1. However, the level of histone H3 ser10 phosphorylation in mitotic cells is similar between JIL-1 mutants and wild type, suggesting that JIL-1 mainly controls histone H3 ser10 phosphorylation in interphase.;JIL-1 kinase domain I (KDI) interacts with Lola ZF5, a splice isoform of the lola locus. Most Lola isoforms belong to the class of BTB (for b&barbelow;ric-a-brac, t&barbelow;ramtrack, and B&barbelow;road-complex) domain containing zinc finger proteins while two of them contain no zinc finger motif. A lola P-element mutation potentially disrupting all isoforms partially suppresses the reduced hatch rate phenotype in JIL-1EP(3)3657/JIL-1 EP(3)3657 embryos. The mode of interaction between lola and JIL-1 is consistent with the general nature of BTB zinc finger proteins as transcription repressors, and suggests possible mechanisms through which other proteins can modify JIL-1 functions or JIL-1 regulates other proteins involved in chromatin organization.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Zhang, Weiguo, "The essential JIL-1 kinase regulates histone H3 phosphorylation and maintains chromatin structure in Drosophila " (2004). Retrospective Theses and Dissertations. 1213.