Replication protein A, class 2b aminoacyl-tRNA synthetases, and related proteins with oligonucleotide/oligosaccharide (OB) fold.; This superfamily includes two oligonucleotide/oligosaccharide binding fold (OBF) domain families. One of these contains the OBF domains of the large (RPA1, 70kDa), middle (RPA2, RPA4, 32kDa) and small (RPA3, 14 kDa) subunits of human heterotrimeric Replication protein A (RPA), and similar domains. RPA is a nuclear single-strand (ss) DNA-binding protein involved in most aspects of DNA metabolism. This family includes the four OBF domains of RPA1 [DNA-binding domain (DBD)-A, DBD-B, DBD-C, and RPA1N], the OBF domain of RPA2 (RPA2 DBD-D), RPA3, and the OBF domain of RPA4. The major DNA binding activity of human RPA and Saccharomyces cerevisiae RPA appears to be associated with DBD-A and -B, of RPA1. RPA1 DBD-C shows only weak ssDNA-binding activity and is involved in trimerization. The other OBF domain family in this superfamily is the N-terminal, anticodon recognition domain of class 2b aminoacyl-tRNA synthetases (aaRSs). aaRSs catalyze the specific attachment of amino acids to their cognate tRNAs during protein biosynthesis. Class 2b aaRSs include the homodimeric aspartyl-, asparaginyl-, and lysyl-tRNA synthetases.

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gi 42573577 122 WIPIIFEGDLAKIAVQHVKKEDRIHVSGKLFIDSPPPNVTYSQSNVQVMVQNLNF 176
Cdd:cd04496  45 WIRVVAFGKLAENAAKYLKKGDLVYVEGRLRTRSWEDKDGQKRYGTEVVADRIEF 99

SSB_OBF: A subfamily of OB folds similar to the OB fold of ssDNA-binding protein (SSB). SSBs bind with high affinity to ssDNA. They bind to and protect ssDNA intermediates during DNA metabolic pathways. All bacterial and eukaryotic SSBs studied to date oligomerize to bring together four OB folds in their active state. The majority (e.g. Escherichia coli SSB) have a single OB fold per monomer, which oligomerize to form a homotetramer. However, Deinococcus and Thermus SSB proteins have two OB folds per monomer, which oligomerize to form a homodimer. Mycobacterium tuberculosis SSB varies in quaternary structure from E. coli SSB. It forms a dimer of dimers having a unique dimer interface, which lends the protein greater stability. Included in this group are OB folds similar to Escherichia coli PriB. E.coli PriB is homodimeric with each monomer having a single OB fold. It does not appear to form higher order oligomers. PriB is an essential protein for the replication restart at forks that have stalled at sites of DNA damage. It also plays a role in the assembly of primosome during replication initiation at the bacteriophage phiX174 origin. PriB physically interacts with SSB and binds ssDNA with high affinity.

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gi 42573577 122 WIPIIFEGDLAKIAVQHVKKEDRIHVSGKLFIDSPPPNVTYSQSNVQVMVQNLNF 176
Cdd:cd04496  45 WIRVVAFGKLAENAAKYLKKGDLVYVEGRLRTRSWEDKDGQKRYGTEVVADRIEF 99

SSB_OBF: A subfamily of OB folds similar to the OB fold of ssDNA-binding protein (SSB). SSBs bind with high affinity to ssDNA. They bind to and protect ssDNA intermediates during DNA metabolic pathways. All bacterial and eukaryotic SSBs studied to date oligomerize to bring together four OB folds in their active state. The majority (e.g. Escherichia coli SSB) have a single OB fold per monomer, which oligomerize to form a homotetramer. However, Deinococcus and Thermus SSB proteins have two OB folds per monomer, which oligomerize to form a homodimer. Mycobacterium tuberculosis SSB varies in quaternary structure from E. coli SSB. It forms a dimer of dimers having a unique dimer interface, which lends the protein greater stability. Included in this group are OB folds similar to Escherichia coli PriB. E.coli PriB is homodimeric with each monomer having a single OB fold. It does not appear to form higher order oligomers. PriB is an essential protein for the replication restart at forks that have stalled at sites of DNA damage. It also plays a role in the assembly of primosome during replication initiation at the bacteriophage phiX174 origin. PriB physically interacts with SSB and binds ssDNA with high affinity.

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                ....*....|....*....|....*....|....*....|....*....|....*
gi 42573577 122 WIPIIFEGDLAKIAVQHVKKEDRIHVSGKLFIDSPPPNVTYSQSNVQVMVQNLNF 176
Cdd:cd04496  45 WIRVVAFGKLAENAAKYLKKGDLVYVEGRLRTRSWEDKDGQKRYGTEVVADRIEF 99