Wg. Gu et al., TARGETING OF MOF, A PUTATIVE HISTONE ACETYL TRANSFERASE, TO THE X-CHROMOSOME OF DROSOPHILA-MELANOGASTER, Developmental genetics, 22(1), 1998, pp. 56-64
Dosage compensation ensures that males with a single X chromosome have
the some amount of most X-linked gene products as females with two X
chromosomes. In Drosophila, this equalization is achieved by a twofold
enhancement of the level of transcription of the X in males relative
to each X chromosome in females. The products of al least five genes,
maleless (mle), male-specific lethal 1, 2, and 3 (msl-1, msl-2, msl-3)
and males absent on the first (mof), ore necessary for dosage compens
ation. The proteins produced by these genes form a complex that is pre
ferentially associated with numerous sites on the X chromosome in soma
tic cells of males but not of females. Binding of the dosage compensat
ion complex to the X chromosome is correlated with a significant incre
ase in the presence of a specific histone isoform, histone 4 acetylate
d at lysine 16, on this chromosome. Experimental results and sequence
analysis suggest that the mof gene encodes an acetyl transferase that
plays a direct role in the specific histone acetylation associated wit
h dosage compensation. Recently RNA transcripts encoded by at least tw
o different genes have also been found associated with the X chromosom
e in males. We have studied the role played by the various components
of the complex in the targeting of MOF to the X chromosome. To this en
d, we have used indirect cytoimmunofluorescence to monitor the binding
of these components in males carrying complete or partial loss-of-fun
ction mutations as well as in XX individuals in which formation of the
dosage compensation complex has been induced by genetic means. (C) 19
98 Wiley-Liss, Inc.