What is single stranded binding protein?

Single-stranded binding (SSB) proteins are a class of proteins that bind to single-stranded DNA (ssDNA) in order to protect it from degradation, help in DNA replication, recombination and repair, and regulate gene expression. These proteins are typically small, monomeric proteins that specifically recognize and bind to ssDNA with high affinity via electrostatic interactions between the negatively charged phosphate backbone of the DNA and positively charged amino acid residues of the SSB protein.

In bacteria, the most well-characterized SSB protein is the E. coli SSB protein (SSBec), which is a tetrameric protein consisting of four identical subunits. It binds to ssDNA in a cooperative manner, meaning that the binding of one subunit increases the affinity of the other subunits for the ssDNA.

In eukaryotes, there are multiple SSB proteins that play different roles in DNA replication, repair, and recombination. For example, replication protein A (RPA) is a trimeric SSB protein that plays a critical role in DNA replication, while the human SSB protein (hSSB1) is involved in DNA repair by promoting the recruitment of repair factors to damage sites.

Overall, SSB proteins are essential for the maintenance of genomic integrity and are conserved across all domains of life.