Sperm chromatin structure and reproductive fitness are altered by substitution of a single amino acid in mouse protamine 1

• Published in: Nature structural & molecular biology Vol. 30; no. 8; pp. 1077 - 1091
• Main Authors: Moritz, Lindsay, Schon, Samantha B., Rabbani, Mashiat, Sheng, Yi, Agrawal, Ritvija, Glass-Klaiber, Juniper, Sultan, Caleb, Camarillo, Jeannie M., Clements, Jourdan, Baldwin, Michael R., Diehl, Adam G., Boyle, Alan P., O’Brien, Patrick J., Ragunathan, Kaushik, Hu, Yueh-Chiang, Kelleher, Neil L., Nandakumar, Jayakrishnan, Li, Jun Z., Orwig, Kyle E., Redding, Sy, Hammoud, Saher Sue
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.08.2023; Nature Publishing Group
• Subjects: 631/337/100; 631/337/100/101; 631/337/458; 631/45/612/100; Alanine; Amino acid substitution; Amino acids; Amino Acids - metabolism; Animals; Arginine; Arginine - metabolism; Biochemistry; Biological Microscopy; Biomedical and Life Sciences; Chromatin; Chromatin - metabolism; Compaction; Deoxyribonucleic acid; DNA; DNA - genetics; DNA - metabolism; DNA biosynthesis; Electrostatic properties; Fertility; Fitness; Genetic Fitness; Life Sciences; Lysine; Male; Males; Membrane Biology; Mice; Phylogeny; Post-translation; Protamine; Protamines - chemistry; Protamines - genetics; Protamines - metabolism; Protein Structure; Reproductive fitness; Residues; Semen - metabolism; Sperm; Sperm Motility; Spermatozoa; Spermiogenesis; Substitutes; Zygotes
• ISSN: 1545-9993; 1545-9985
• DOI: 10.1038/s41594-023-01033-4

Conventional dogma presumes that protamine-mediated DNA compaction in sperm is achieved by electrostatic interactions between DNA and the arginine-rich core of protamines. Phylogenetic analysis reveals several non-arginine residues conserved within, but not across species. The significance of these residues and their post-translational modifications are poorly understood. Here, we investigated the role of K49, a rodent-specific lysine residue in protamine 1 (P1) that is acetylated early in spermiogenesis and retained in sperm. In sperm, alanine substitution (P1(K49A)) decreases sperm motility and male fertility—defects that are not rescued by arginine substitution (P1(K49R)). In zygotes, P1(K49A) leads to premature male pronuclear decompaction, altered DNA replication, and embryonic arrest. In vitro, P1(K49A) decreases protamine–DNA binding and alters DNA compaction and decompaction kinetics. Hence, a single amino acid substitution outside the P1 arginine core is sufficient to profoundly alter protein function and developmental outcomes, suggesting that protamine non-arginine residues are essential for reproductive fitness. Here, the authors show that a single substitution in mouse P1, outside of its arginine core and independently of its charge, suffices to alter sperm chromatin structure and associated developmental outcomes.