Novel insight into the composition of human single-stranded DNA-binding protein 1 (hSSB1)-containing protein complexes.

Nicholas W Ashton,Derek J Richard,Dorothy Loo,Kenneth J O’Byrne,Nicolas Paquet

doi:10.1186/s12867-016-0077-5

Abstract

BackgroundSingle-stranded DNA-binding proteins are essential cellular components required for the protection, metabolism and processing of single-stranded DNA. Human single-stranded DNA-binding protein 1 (hSSB1) is one such protein, with described roles in genome stability maintenance and transcriptional regulation. As yet, however, the mechanisms through which hSSB1 functions and the binding partners with which it interacts remain poorly understood.ResultsIn this work, hSSB1 was immunoprecipitated from cell lysate samples that had been enriched for non-soluble nuclear proteins and those associating with hSSB1 identified by mass spectrometry. In doing so, 334 potential hSSB1-associating proteins were identified, with known roles in a range of distinct biological processes. Unexpectedly, whilst hSSB1 has largely been studied in a genome stability context, few other DNA repair or replication proteins were detected. By contrast, a large number of proteins were identified with roles in mRNA metabolism, reflecting a currently emerging area of hSSB1 study. In addition, numerous proteins were detected that comprise various chromatin-remodelling complexes.ConclusionsThese findings provide new insight into the binding partners of hSSB1 and will likely function as a platform for future research.Electronic supplementary materialThe online version of this article (doi:10.1186/s12867-016-0077-5) contains supplementary material, which is available to authorized users.

Highlights

Single-stranded DNA-binding proteins are essential cellular components required for the protection, metabolism and processing of single-stranded DNA
Immunoprecipitation of Human single-stranded DNA-binding protein 1 (hSSB1) from samples enriched for non‐soluble nuclear proteins To further elucidate the role of hSSB1 in single-stranded DNA (ssDNA) metabolism, we sought to identify other proteins with which hSSB1 may associate at chromatin
To assess the efficacy of this technique, the soluble and non-soluble nuclear fractions were immunoblotted with antibodies against nucleolin, a protein expected to be largely soluble under these conditions [29], as well as the chromatin-associated protein, histone H3 (Fig. 1b)

Summary

Introduction

Single-stranded DNA-binding proteins are essential cellular components required for the protection, metabolism and processing of single-stranded DNA. Human single-stranded DNA-binding protein 1 (hSSB1) is one such protein, with described roles in genome stability maintenance and transcriptional regulation. The recurrent exposure of single-stranded DNA (ssDNA) is a central aspect of cellular metabolism, permitting processes that include RNA transcription and DNA replication. SsDNA is frequently exposed as a result of DNA damage, both as a direct result of lesion formation, as well as subsequently during repair transactions [3]. In all of these processes, ssDNA-binding proteins are required for proper manipulation of the DNA, ensuring it is maintained in ssDNA-binding proteins can associate with ssDNA via a number of binding motifs.

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