DF 31, a sperm decondensation factor from Drosophila melanogaster: purification and characterization.

Abstract

We have purified to homogeneity a Drosophila protein which is able to decondense Xenopus sperm chromatin. This protein, which we have called DF 31, is a heat‐stable phosphoprotein which displays a molecular weight of 31 kDa on SDS‐PAGE, but which has an apparent molecular weight of > 200 kDa on gel filtration. We show that DF 31 decondenses sperm DNA by displacement of sperm‐specific proteins. In addition to its sperm decondensation activity, DF 31 is also able to facilitate nucleosome loading on both decondensed sperm DNA and on naked DNA template. The reaction as catalysed by DF 31 is quite efficient; however, the nucleosomes appear to be loaded randomly onto the DNA, not in regular arrays. Although the mechanism by which DF 31 aids nucleosome loading is not yet clear, it most probably occurs through binding of DF 31 to core histones.

Sperm Chromatin Decondensation by Template Activating Factor I through Direct Interaction with Basic Proteins

“…Two heat-stable factors, p22/CRP1 and DF31/CRP2, were purified based on the decondensation activity (7,8,24). Drosophila NAP-I was also shown to decondense Xenopus sperm chromatin (21).…”

“…Demembraned Xenopus sperm chromatin is decondensed by incubation with Xenopus egg extracts in cell-free systems (11,12,23,34,42,46). In the past decade, demembraned Xenopus sperm chromatin has been used extensively to study functions of histone binding proteins (7,21,24,42,45,46). Again first studied was nucleoplasmin, which is most likely the actual player to decondense sperm chromatin in Xenopus eggs (42,46).…”

“…Depletion of nucleoplasmin from egg extracts results in a much lower rate of chromatin decondensation than that in the mock-depleted control extracts (46). Recently, Drosophila embryo extracts used to study the nucleosome assembly and fractionation of the extracts led to the identification of factors that decondense Xenopus sperm chromatin (6,7,(19)(20)(21)24). Thus, it is thought that factors which had been found originally as nucleosome assembly factors can be involved in remodeling of chromatin structure.…”

Drosophila TAP/p32 is a core histone chaperone that cooperates with NAP-1, NLP, and nucleophosmin in sperm chromatin remodeling during fertilization

“…Sperm chromatin remodeling (SCR) is controlled by biochemical activities in the early oocyte, but components of these activities remain largely unknown (McLay and Clarke 2003). However various protein factors have been implicated in SCR, including core histone chaperones from Xenopus (Nucleoplasmin, N1, HIRA, and TAF-I) and Drosophila (NAP-1, p22, DF31, HIRA, and Yemanuclein) (Dilworth et al 1987;Philpott and Leno 1992;Kawasaki et al 1994;Crevel and Cotterill 1995;Ito et al 1996a;Matsumoto et al 1999;Loppin et al 2001;Ray-Gallet et al 2002;Orsi et al 2013). In mammals, members of nucleoplasmin/nucleophosmin family proteins (NPM1-3) function in sperm chromatin decondensation in vitro (Okuwaki et al 2012).…”

Chromatin assembly factors: a dual function in nucleosome formation and mobilization?

“…These corehistone-binding proteins include nucleoplasmin (Laskey et al 1978;Earnshaw et al 1980;Sealy et al 1986;Bürglin et al 1987;Dingwall et al 1987), N1/ N2 (Kleinschmidt & Franke 1982;Kleinschmidt et al 1985Kleinschmidt et al , 1986Dilworth et al 1987), NAP-1 (also known as AP-I, Ishimi et al 1984Ishimi et al , 1987Ishimi & Kikuchi 1991;Ito et al 1996a), CAF-1 (Stillman 1986;Smith & Stillman 1989Kaufman et al 1995;Tyler et al 1996;Verreault et al 1996;Ito et al 1997), dNLP/CRP1 (Ito et al 1996b;Crevel et al 1997), Spt6 (Bortvin & Winston 1996), and DF 31 (Crevel & Cotterill 1995). In addition, there are likely to be other histone-binding proteins that have yet to be discovered.…”