Purification and characterization of fertility‐associated antigen (FAA) in bovine seminal fluid

Abstract

Heparin-binding proteins (HBP) recognized by a monoclonal antibody (M1) are produced by male accessory sex glands and bind to distinct regions of ejaculated bull sperm. Immunoblots of sperm proteins probed with M1 identified HBP variants of approximately 31-, 24-, and 21.5-kDa that were associated with increased fertility of bulls. The purpose of this study was to identify the 31-kDa HBP known as fertility-associated antigen (FAA). FAA was isolated by heparin-affinity chromatography and reversed-phase high performance liquid chromatography near homogeneity. Biochemical characterization indicated that FAA was an unglycosylated, basic protein. FAA protein was detected in seminal vesicle and prostate gland homogenates, and FAA extracted from sperm membranes by treatment with hypertonic media was identical biochemically to seminal fluid-derived FAA. N-terminal sequence analysis of purified FAA yielded a 26 amino acid sequence (L K I X S F N V R S F G E S K K A G F N A M R V I V) with 73% identity to a recently identified human deoxyribonuclease (DNase) I-like protein. Two internal amino acid sequences generated from lys-C digested FAA were 85% and 92% identical to the same DNase I-like protein. In conclusion, we have identified a bovine seminal heparin-binding protein that binds to sperm and is indicative of bull fertility as being similar to the family of DNase I-like proteins. These data demonstrate the presence of a novel DNase I-like protein in bull accessory sex glands and form the groundwork for the identification of a candidate genetic marker for fertility of bulls.

Comprehensive mapping of the bull sperm surface proteome

“…Many putative markers of bull fertility known from either classical or molecular genetic studies were identified in the current study, showing the biological relevance of our membrane‐enriched population. These include well‐characterized sperm proteins such as fibronectin‐domain containing proteins [BSP1 (PDC‐109), BSP3 (BSP‐A3), BSP5 (BSP‐30), and ELSPBP1]; spermadhesins [SPADH1 (ASFP), and SPADH2 (Z13)]; proteins belonging to the proteasome (PSMD6) and CCT complex (CCT5, CCT8), as well as AK1, DNASE1L3 (FAA), PLA2G7, and PTGDS (PGDS) . Disintegrin and metalloproteinase (ADAM) proteins are also known to be involved in the mediation of sperm function .…”

“…Genes whose function did not fall within these functional categories were classified as uncharacterised (Supporting Information Table S1). Proteins known to be associated with the fertility and function of bull sperm were identified from previous studies .…”

Polysialic Acid Is Present in Mammalian Semen as a Post-translational Modification of the Neural Cell Adhesion Molecule NCAM and the Polysialyltransferase ST8SiaII

“…DNase of the seminal plasma, however, degrades DNA, and spermatozoa can escape from this system. Interestingly, high levels of DNase in seminal plasma have been associated with higher fertility in bovine systems (66,67). The most cytotoxic entities of NET for endogenous cells, however, are the extracellular histones (68).…”

Recombinant binder of sperm protein1 (rec-BSP1) as a potent fertility factor mediates its effect on spermatozoa and production of blastocysts in buffalo

“…The binding induces conformational changes in the BSPs, which in turn induce cholesterol efflux, sperm capacitation and trigger acrosome reaction (19). The association of different ligands with BSPs has widely been studied to investigate the effect of fertility in males (20). However, the ligandbinding mechanism for rec-BSP1 and the function of rec-BSP1-ligand complexes are poorly explored.…”