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A distinctive single‐stranded DNA‐binding protein from the Archaeon Sulfolobus solfataricus
Author(s) -
Haseltine Cynthia A.,
Kowalczykowski Stephen C.
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02807.x
Subject(s) - sulfolobus solfataricus , methanococcus , biology , sulfolobus , biochemistry , dna , replication protein a , single stranded binding protein , dna binding protein , dna binding domain , hmg box , dna replication , binding domain , microbiology and biotechnology , binding site , escherichia coli , gene , archaea , transcription factor
Summary Single‐stranded DNA binding proteins (SSBs) have been identified in all three domains of life. Here, we report the identification of a novel crenarchaeal SSB protein that is distinctly different from its euryar‐chaeal counterparts. Rather than comprising four DNA‐binding domains and a zinc‐finger motif within a single polypeptide of 645 amino acids, as for Methanococcus jannaschii , the Sulfolobus solfataricus SSB protein (SsoSSB) has a single DNA‐binding domain in a polypeptide of just 148 amino acids with a eubacterial‐like acidic C‐terminus. SsoSSB protein was purified to homogeneity and found to form tetramers in solution, suggesting a quaternary structure analogous to that of E. coli SSB protein, despite possessing DNA‐binding domains more similar to those of eukaryotic Replication Protein A (RPA). We demonstrate distributive binding of SsoSSB to ssDNA at high temperature with an apparent site size of approximately five nucleotides (nt) per monomer. Additionally, the protein is functional both in vitro and in vivo , stimulating RecA protein‐mediated DNA strand‐exchange and rescuing the ssb‐1 lethal mutation of E. coli respectively. We dis‐cuss possible evolutionary relationships amongst the various members of the SSB/RPA family.