Characterization of human sperm protamine proteoforms through a combination of top-down and bottom-up mass spectrometry approaches

ABSTRACT: Protamine 1 (P1) and protamine 2 family (P2) are the most abundant nuclear basic spermspecific proteins, packing 85-95% of the paternal DNA. P1 is synthesized as a mature form, whereas P2 components (HP2, HP3 and HP4) arise from the proteolysis of the precursor (pre-P2). Due to the particular protamine physical-chemical properties, their identification by standardized bottom-up mass spectrometry (MS) strategies are not straightforward. Therefore, the aim of this study was to identify the sperm protamine proteoforms profile including P1 and P2 members and their post-translational modifications in normozoospermic individuals using two complementary strategies, a top-down MS approach and a proteinase K-digestion based bottom-up MS approach. By top-down MS approach, both described and new truncated P1 and pre-P2 proteoforms were identified. Likewise, intact P1, pre-P2, and P2 mature forms and their phosphorylation pattern were detected, as well as a +61 Da modification in different proteoforms. Additionally, the bottom-up MS approach revealed phosphorylated residues for pre-P2 and the new P2 isoform 2, which is not annotated at UniProtKB database. Implementing these strategies in comparative studies of different infertile phenotypes would permit to determine alterations in the protamine proteoforms pattern and elucidate the role of phosphorylation/dephosphorylation dynamics in male fertility.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Semen, Sperm

SUBMITTER: Marina Gay  

LAB HEAD: Rafael Oliva

PROVIDER: PXD014618 | Pride | 2019-11-11

REPOSITORIES: Pride