AreA is a transcription activation protein regulating over 100 genes in Aspergillus nidulans. It is a member of the 4 cysteine zinc finger family, with significant sequence homology in the zinc finger domain with related proteins. As with similar proteins, the zinc finger domain has been identified as the DNA binding motif. Other regions of the protein do not appear to playa role in directly binding DNA. A truncated form of AreA, known as the minimal zinc finger protein, containing the zinc finger domain alone, has been cloned and over-expressed in this study. This domain is sufficient to bind DNA specifically, but weakly. However, the addition of a further 30 amino acids, C-terminal to the minimal zinc finger, containing a highly basic tail is shown to increase the specific binding affinity. Other forms of AreA have been characterised and do not significantly increase the affinity of DNA binding. Identification of a consensus binding sequence by SELEX has also demonstrated that the minimal zinc finger is sufficient to specifically recognise the core sequence GA T A but suggests a degree of tolerance for TAT A. Addition of further regions of the protein do not extend the limits of the recognition sequence or change the consensus sequence. The SELEX experiments did not give any evidence of AreA functioning as a dimer, through proteinprotein interactions. Structural studies of the truncated forms of AreA, by circular dichroism, have suggested the formation of secondary structures for the zinc finger motif similar to those of other proteins and in agreement with the published NMR structure of the AreA zinc finger bound to DNA (Starich et ai., 1998a).
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:264456 |
| Date | January 1998 |
| Creators | Reynolds, Lindsey |
| Publisher | University of Portsmouth |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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