The chromodomain protein, Chromator, interacts with JIL-1 kinase and regulates the structure ofDrosophilapolytene chromosomes

Abstract

In this study we have generated two new hypomorphic Chro alleles and analyzed the consequences of reduced Chromator protein function on polytene chromosome structure. We show that in Chro 71 /Chro 612 mutants the polytene chromosome arms were coiled and compacted with a disruption and misalignment of band and interband regions and with numerous ectopic contacts connecting non-homologous regions. Furthermore, we demonstrate that Chromator co-localizes with the JIL-1 kinase at polytene interband regions and that the two proteins interact within the same protein complex. That both proteins are necessary and may function together is supported by the finding that a concomitant reduction in JIL-1 and Chromator function synergistically reduces viability during development. Overlay assays and deletion construct analysis suggested that the interaction between JIL-1 and Chromator is direct and that it is mediated by sequences in the C-terminal domain of Chromator and by the acidic region within the C-terminal domain of JIL-1. Taken together these findings indicate that Chromator and JIL-1 interact in an interband-specific complex that functions to establish or maintain polytene chromosome structure in Drosophila.

Loss of ATAC-specific acetylation of histone H4 at Lys12 reduces binding of JIL-1 to chromatin and phosphorylation of histone H3 at Ser10

“…Mutations affecting the JIL-1 kinase (Wang et al, 2001), subunits of the NURF chromatin-remodeling complex (iswi and nurf alleles) (Badenhorst et al, 2002;Badenhorst et al, 2005;Deuring et al, 2000) as well as other chromatin-associated proteins, such as SU(VAR)205 (also known as HP1), SU(VAR)3-7 (Spierer et al, 2005) and Chromator (also known as Chriz) (Eggert et al, 2004;Rath et al, 2006), each result in structural defects of chromatin. The distortions are most clearly seen in the structure of male X chromosomes, resulting in the appearance of a puffed-X morphology, also referred to as 'bloated male X' or 'pompon' phenotype (Zhimulev, 1996).…”

Dissection of open chromatin domain formation by site-specific recombination in Drosophila

“…We observed prominent binding of Chriz, Z4 (data not shown) and Jil-1, proteins that are typically found in decondensed chromatin as reported previously (Eggert et al, 2004;Gortchakov et al, 2005;Wang et al, 2001). Chriz and Jil-1 physically interact (Rath et al, 2006), and on Chriz knockdown both Jil-1 chromosomal binding and H3S10 phosphorylation are dramatically reduced, indicating that Chriz is required for chromosomal targeting of Jil-1 (Gan et al, 2011). Forced local recruitment of active Jil-1 kinase results in local chromatin decondensation (Deng et al, 2008).…”

“…Forced local recruitment of active Jil-1 kinase results in local chromatin decondensation (Deng et al, 2008). Hypomorphic mutations in Jil-1 and Chriz, by contrast, result in chromosome condensation and loss of interphase chromatin structure (Wang et al, 2001;Rath et al, 2006, Gan et al, 2011, similar to what is observed on loss of Z4 protein (Eggert et al, 2004). Besides these factors, we observed binding of the insulator proteins CP190 (Whitfield et al, 1988;Pai et al, 2004) and BEAF 32 (Zhao et al, 1995; data not shown) to the ectopic 61C7-8 position, resembling the situation at the endogenous site.…”

“…A set of proteins mainly recruited to interband chromatin might play a role in open chromatin formation. Besides paused forms of RNA polymerase II, these include nucleosome-remodeling and histone-modifying proteins like Brahma, TRX and the H3S10 kinase Jil-1 (Wang et al, 2001), insulator proteins like BEAF32AB, CP190 and the Drosophila homolog of CTCF (dCTCF) (Van Bortle and Corces, 2012) and proteins of as yet unknown function, like Chriz (also known as Chro) (Gortchakov et al, 2005;Rath et al, 2006) and Z4 (also known as Pzg) (Eggert et al, 2004). Furthermore, interband chromatin is enriched for 'activating' chromatin modifications, like acetylation (H4K16ac and H3K9ac), methylation (H3K4me3) and phosphorylation (phospho-H3S10) Demakov et al, 2011).…”

Chromatin-Associated Proteins HP1 and Mod(mdg4) Modify Y-Linked Regulatory Variation in the Drosophila Testis

“…Experimental evidence indicates that Mod (mdg4) is involved in meiosis I and chromosome segregation in males (Soltani-Bejnood et al 2007), in the regulation of chromatin assembly or disassembly (Gerasimova et al 1995), oogenesis (Buchner et al 2000), and germ-cell migration (Read et al 2000). JIL-1 has histone kinase activity (Jin et al 1999;Rath et al 2006;Zhang et al 2006) and is involved in the negative regulation of chromatin silencing and in chromosome organization. Deficiency of JIL-1 leads to strong enhancer of variegation (white-eye phenotype), counteracting even the suppressor-of-variegation effect of HP1 and Su(var)3-9 (Wang et al 2011).…”