Nucleoplasmin remodels sperm chromatin in Xenopus egg extracts.
Nucleoplasmin is necessary and sufficient for the initial stage of Xenopus sperm decondensation in egg extracts. In this article we show that sperm decondensation is accompanied by loss of two sperm-specific basic proteins (X and Y) and gain of histones H2A and H2B, resulting in nucleosome formation. Purified nucleoplasmin alone removes X and Y and assembles purified H2A and H2B on decondensing sperm chromatin, forming nucleosome cores. Immunodepletion of nucleoplasmin from extract prevents removal of X and Y and addition of H2A and H2B, while adding back nucleoplasmin restores decondensation and X and Y removal. Thus, nucleoplasmin acts as both an assembly and a disassembly factor for remodeling sperm chromatin at fertilization.
Philpott
A
A
Wellcome/CRC Institute of Cancer and Developmental Biology, University of Cambridge, England.
Leno
G H
GH
D000818:Animals; D002457:Cell Extracts; D002843:Chromatin / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006657:Histones / Q000378:metabolism; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism*; D056489:Nucleoplasmins; D009707:Nucleosomes / Q000378:metabolism; D010063:Ovum / Q000378:metabolism*; D010750:Phosphoproteins; D011233:Precipitin Tests; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000378:metabolism*; D014982:Xenopus laevis
D002457:Cell Extracts; D002843:Chromatin; D006657:Histones; D009687:Nuclear Proteins; D056489:Nucleoplasmins; D009707:Nucleosomes; D010750:Phosphoproteins; C026588:sperm basic nuclear proteins