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Mapping of post-translational modifications of transition proteins, TP1 and TP2, and identification of protein arginine methyltransferase 4 and lysine methyltransferase 7 as methyltransferase for TP2

Gupta, N and Madapura, MP and Bhat, UA and Rao, MRS (2015) 'Mapping of post-translational modifications of transition proteins, TP1 and TP2, and identification of protein arginine methyltransferase 4 and lysine methyltransferase 7 as methyltransferase for TP2.' Journal of Biological Chemistry, 290 (19). 12101 - 12122. ISSN 0021-9258

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Abstract

© 2015 by The American Society for Biochemistry and Molecular Biology, Inc. In a unique global chromatin remodeling process during mammalian spermiogenesis, 90% of the nucleosomal histones are replaced by testis-specific transition proteins, TP1, TP2, and TP4. These proteins are further substituted by sperm-specific protamines, P1 and P2, to form a highly condensed sperm chromatin. In spermatozoa, a small proportion of chromatin, which ranges from 1 to 10% in mammals, retains the nucleosomal architecture and is implicated to play a role in transgenerational inheritance. However, there is still no mechanistic understanding of the interaction of chromatin machinery with histones and transition proteins, which facilitate this selective histone replacement from chromatin. Here, we report the identification of 16 and 19 novel post-translational modifications on rat endogenous transition proteins, TP1 and TP2, respectively, by mass spectrometry. By in vitro assays and mutational analysis, we demonstrate that protein arginine methyltransferase PRMT4 (CARM1) methylates TP2 at Arg<sup>71</sup>, Arg<sup>75</sup>, and Arg<sup>92</sup>residues, and lysine methyltransferase KMT7 (Set9) methylates TP2 at Lys<sup>88</sup> and Lys<sup>91</sup> residues. Further studies with modification-specific antibodies that recognize TP2K88me1 and TP2R92me1 modifications showed that they appear in elongating to condensing spermatids and predominantly associated with the chromatin-bound TP2. This work establishes the repertoire of post-translational modifications that occur on TP1 and TP2, which may play a significant role in various chromatin-templated events during spermiogenesis and in the establishment of the sperm epigenome.

Item Type: Article
Subjects: Q Science > QH Natural history > QH426 Genetics
Divisions: Faculty of Science and Health > Biological Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 23 Nov 2015 10:42
Last Modified: 30 Jan 2019 16:23
URI: http://repository.essex.ac.uk/id/eprint/15289

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