Single strand DNA-binding proteins (SSB) play vital roles in a number of cellular processes such as DNA replication, recombination and repair. There is evidence that they also interact specifically with a variety of other proteins which are involved in these processes including DNA polymerases and exonucleases.
Herbaspirillum seropedicae is a b-proteobacteria and an obligate endophytic diazotroph found in association with grasses, rice, and sugarcane. In this work, we describe the expression, purification and initial structural and functional characterization of a single strand binding protein from H. seropedicae. Its amino acid sequence shows high identity with single strand binding proteins of other microorganisms. Mass spectrometry data confirmed the identity of this protein and also the coincidence between theoretical predicted molecular weight with that of the purified recombinant protein. The apparent molecular mass of the native SSB from H. seropedicae was estimated by gel filtration, suggesting that the native protein is a trimer made up of three similar subunits. Thermal denaturation monitored by UV absorption suggested proper folding of the recombinant protein. Gel mobility shift assays showed the interaction between SSB and single strand DNA (ssDNA). Further Biochemical and functional properties of this protein are under investigation.