Single stranded binding protein: Difference between revisions
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==Other SSB Structures== | ==Other SSB Structures== | ||
<StructureSection load='2vw9' size='400' side='left' frame='true' caption='Structure of Single Stranded DNA-Binding Protein from | <StructureSection load='2vw9' size='400' side='left' frame='true' caption='Structure of Single Stranded DNA-Binding Protein from Helicobacter pylori bound to ssDNA (PDB entry [[2vw9]])' scene=''> | ||
Though the SSB of ''E. coli'' is perhaps the best characterized, ssDNA binding proteins of many other organisms have also been identified. Some proteins, such as the SSB of ''E. coli'' and human mitochondrial SSBs, bind as tetramers to ssDNA. However, the SSB can have from one to as many as four OB-fold containing subunits in its structure. For example, the structure of the SSB from ''Helicobacter pylori'' shown to the left is a homodimer composed of two identical subunits, each with the an OB-fold motif made of similar secondary structure elements such as an <scene name='56/566528/Alpha_helices/3'>α-helix</scene>and several <scene name='56/566528/Beta_sheets/1'>β-sheets</scene>. Just like in the ''E. coli'' SSB, the OB-fold area in each subunit is used for single-stranded nucleic acid binding. A phenylalanine residue (<scene name='56/566528/Phe_56/1'>Phe56</scene>) is again integral to ssDNA binding, as it is a site of cross-linking. Tryptophan and lysine residues again play an important role in binding of ssDNA to the protein. | Though the SSB of ''E. coli'' is perhaps the best characterized, ssDNA binding proteins of many other organisms have also been identified. Some proteins, such as the SSB of ''E. coli'' and human mitochondrial SSBs, bind as tetramers to ssDNA. However, the SSB can have from one to as many as four OB-fold containing subunits in its structure. For example, the structure of the SSB from ''Helicobacter pylori'' shown to the left is a homodimer composed of two identical subunits, each with the an OB-fold motif made of similar secondary structure elements such as an <scene name='56/566528/Alpha_helices/3'>α-helix</scene>and several <scene name='56/566528/Beta_sheets/1'>β-sheets</scene>. Just like in the ''E. coli'' SSB, the OB-fold area in each subunit is used for single-stranded nucleic acid binding. A phenylalanine residue (<scene name='56/566528/Phe_56/1'>Phe56</scene>) is again integral to ssDNA binding, as it is a site of cross-linking. Tryptophan and lysine residues again play an important role in binding of ssDNA to the protein. | ||