Protein Family Models

Date:

2024-08-14

Date:

2024-08-14

The Escherichia coli Ada protein repairs O6-methylguanine residues and methyl phosphotriesters in DNA by direct transfer of the methyl group to a cysteine residue. This domain contains four conserved cysteines that form a zinc binding site [1,2]. One of these cysteines is a methyl group acceptor. The methylated domain can then specifically bind to the ada box on a DNA duplex [2]. [1]. 1581309. Zinc binding by the methylation signaling domain of the Escherichia coli Ada protein. Myers LC, Terranova MP, Nash HM, Markus MA, Verdine GL;. Biochemistry 1992;31:4541-4547. [2]. 8500619. Folding topology and DNA binding of the N-terminal fragment of Ada protein. Sakashita H, Sakuma T, Ohkubo T, Kainosho M, Sakumi K, Sekiguchi M, Morikawa K;. FEBS Lett 1993;323:252-256. (from Pfam)

Date:

2024-10-16

In the absence of arabinose, the N-terminal arm of AraC binds to the DNA binding domain (Pfam:PF00165) and helps to hold the two DNA binding domains in a relative orientation that favours DNA looping. In the presence of arabinose, the arms bind over the arabinose on the dimerisation domain, thus freeing the DNA-binding domains. The freed DNA-binding domains are then able to assume a conformation suitable for binding to the adjacent DNA sites that are utilised when AraC activates transcription, and hence AraC ceases looping the DNA when arabinose is added [1-2]. [1]. 9600836. Apo-AraC actively seeks to loop. Seabold RR, Schleif RF;. J Mol Biol 1998;278:529-538. [2]. 9600837. Arm-domain interactions in AraC. Saviola B, Seabold R, Schleif RF;. J Mol Biol 1998;278:539-548. (from Pfam)

Date:

2024-10-16