A Dimeric Mutant of the Homotetrameric Single-Stranded DNA Binding Protein from Escherichia coli

M. Landwehr, U. Curth and C. Urbanke

Abstract

A single amino acid substitution (Y78R) at the dimerdimer interface of homotetrameric single stranded DNA binding protein from E.coli (EcoSSB) renders the protein a stable dimer. This dimer can bind singlestranded DNA albeit with greatly reduced affinity. In vivo this dimeric SSB cannot replace homotetrameric EcoSSB. Amino acid changes at the rim of the dimerdimer interface nearby (Q76K, Q76E) show an electrostatic interaction between a charged amino acid at position 76 and bound nucleic acid. In conclusion, nucleic acid binding to homotetrameric SSB must take place across both dimers to achieve functionally correct binding.

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Biological Chemistry keeps you up-to-date with the latest advances in the molecular life sciences. The journal publishes Research Articles, Short Communications, Reviews and Minireviews. Areas include: general biochemistry/pathobiochemistry, structural biology, molecular and cellular biology, genetics and epigenetics, virology, molecular medicine, plant molecular biology/biochemistry and novel experimental methodologies.

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