InterPro: IPR001510 Zinc finger, PARP-type

Zinc finger (Znf) domains are relatively small protein motifs which contain multiple finger-like protrusions that make tandem contacts with their target molecule. Some of these domains bind zinc, but many do not; instead binding other metals such as iron, or no metal at all. For example, some family members form salt bridges to stabilise the finger-like folds. They were first identified as a DNA-binding motif in transcription factor TFIIIA from Xenopus laevis (African clawed frog), however they are now recognised to bind DNA, RNA, protein and/or lipid substrates [1, 2, 3, 4, 5]. Their binding properties depend on the amino acid sequence of the finger domains and of the linker between fingers, as well as on the higher-order structures and the number of fingers. Znf domains are often found in clusters, where fingers can have different binding specificities. There are many superfamilies of Znf motifs, varying in both sequence and structure. They display considerable versatility in binding modes, even between members of the same class (e.g. some bind DNA, others protein), suggesting that Znf motifs are stable scaffolds that have evolved specialised functions. For example, Znf-containing proteins function in gene transcription, translation, mRNA trafficking, cytoskeleton organisation, epithelial development, cell adhesion, protein folding, chromatin remodelling and zinc sensing, to name but a few [6]. Zinc-binding motifs are stable structures, and they rarely undergo conformational changes upon binding their target.

This entry represents PARP (Poly(ADP) polymerase) type zinc finger domains.

NAD(+) ADP-ribosyltransferase(EC:2.4.2.30) [7, 8] is a eukaryotic enzyme that catalyses the covalent attachment of ADP-ribose units from NAD(+) to various nuclear acceptor proteins. This post-translational modification of nuclear proteins is dependent on DNA. It appears to be involved in the regulation of various important cellular processes such as differentiation, proliferation and tumour transformation as well as in the regulation of the molecular events involved in the recovery of the cell from DNA damage. Structurally, NAD(+) ADP-ribosyltransferase consists of three distinct domains: an N-terminal zinc-dependent DNA-binding domain, a central automodification domain and a C-terminal NAD-binding domain. The DNA-binding region contains a pair of PARP-type zinc finger domains which have been shown to bind DNA in a zinc-dependent manner. The PARP-type zinc finger domains seem to bind specifically to single-stranded DNA and to act as a DNA nick sensor. DNA ligase III [9] contains, in its N-terminal section, a single copy of a zinc finger highly similar to those of PARP.

More information about these proteins can be found at Protein of the Month: Zinc Fingers [10].