CHARACTERIZATION OF THE DWNN DOMAIN AND RING FINGER-LIKE MOTIF WITHIN THE DCM OF THE Drosophila melanogaster SNAMA PROTEIN
Year: 2008
Type: dissertation
Abstract: SNAMA is a 139 kDa Drosophila melanogaster protein belonging to the \nRetinoblastoma Binding Protein 6 (RbBP6) superfamily. Mammalian \nRbBP6 interacts with both p53 and Rb and plays a critical role in \nembryonic development and tumorigenesis as a negative regulator of p53. \nAll RbBP6 members contain a 5´ DWNN Catalytic Domain (DCM) \nconsisting of a DWNN (domain with no name) domain followed by a zinc \nfinger and RING (really interesting new gene) finger motif. RING finger \nand U-box ubiquitin ligases are dependent on their RING finger \nconformation for their ubiquitin ligase activity. The main focus of this work \nwas to further elucidate the functional characteristics of the DCM within \nSNAMA. This was achieved by examinining transcription regulation of the \nSNAMA gene and determining whether SNAMA exhibits ubiquitin ligase \nactivity. 5´ Rapid amplification of cDNA ends (RACE) was used to \ndetermine the core promoter elements of SNAMA through the discovery of \nthe transcription initiation site. Ubiquitin conjugation assays using pure \nrecombinant SNAMA as the ubiquitin ligase were performed to analyze the \nubiquitin ligase activity of the protein. Transcriptional regulation of the \nSNAMA gene is achieved through a single TATA-less promoter that gives \nrise to a single transcript of 3.9 kb. Furthermore, this work shows that \nSNAMA is a unique RING finger ubiquitin ligase that is capable of autoubiquitination \nin the absence of zinc ions. This activity is dependent on its \nRING finger-like motif, which has greatest specificity to the UbcH5a \nconjugating enzyme. Furthermore, SNAMA relies on E1, E2, ATP, and \nubiquitin for its E3 activity. Thus, SNAMA is the first member of the \nRbBP6 family to portray RING finger ubiquitin ligase activity and \nrepresents a “drugable” target for pharmaceutical intervention.
Author: Ricardo Antunes
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Funder: National Research Foundation
OpenAlex ID: W2154281481