title: A sperm nuclear basic protein from the sperm of the marine worm Chaetopterus variopedatus with sequence similarity to the arginine-rich C-termini of chordate protamine-likes.
abstract: The sperm nuclear basic proteins (SNBPs) of the marine annelid worm Chaetopterus variopedatus have been shown previously to consist of a mixture of two SNBPs: histone H1-like (CvH1) and C.variopedatus protamine-like (CvPL). Here, we report the structural characterization of CvPL. The protein has a molecular weight of 8370.5 Da, a K/R ratio of 0.34, and a secondary structure, which are intermediate between those of protamine (P) and protamine-like (PL) SNBPs. The N-terminal sequence of CvPL shows a high extent of similarity with the arginine-rich C-terminal domain of chordate PL-type SNBPs. Furthermore, the protein binds to DNA in a similar fashion as vertebrate PLs and their own CvH1, but in a way that is different from that of the lysine-rich somatic H1 histones. We have experimentally determined the molar ratio CvH1:CvPL to be ∼1:6 in C. variopedatus sperm. Based on all of these, a model is proposed for the organization of the sperm chromatin by CvH1 and CvPL.
authors.affiliation: Department of Structural and Functional Biology, University of Naples Federico II, Napoli, Italy.
authors.forename: Flavia Marialucia
authors.initials: FM
authors.lastname: Fioretti
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Febbraio
authors.forename: Antonietta
authors.initials: A
authors.lastname: Carbone
authors.forename: Margherita
authors.initials: M
authors.lastname: Branno
authors.forename: Vitale
authors.initials: V
authors.lastname: Carratore
authors.forename: Laura
authors.initials: L
authors.lastname: Fucci
authors.forename: Juan
authors.initials: J
authors.lastname: Ausió
authors.forename: Marina
authors.initials: M
authors.lastname: Piscopo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D008297:Male; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry*; D011077:Polychaeta / Q000737:chemistry*; D011479:Protamines / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013094:Spermatozoa / Q000737:chemistry*
chemical_list: D009687:Nuclear Proteins; D011479:Protamines; C026588:sperm basic nuclear proteins