Single-stranded DNA-binding protein, molecular model. The function of single-strand binding protein (SSB) is to bind to single strands of DNA (deoxyribonucleic acid) that form as DNA replicated. This protein stabilises the strands and prevents them recombining to form double-stranded DNA (reannealing). This example is from Mycobacterium tuberculosis, the bacterium that causes tuberculosis. The protein is hence known as MtuSSB, and has differences and similarities to the SSBs found in other bacteria and human mitochondria. It consists of two chains (purple and red), with a total of 164 amino acids.