Structural Insights into Ankyrin Repeat-Containing Proteins and Their Influence in Ubiquitylation

Abstract

Ankyrin repeat (AR) domains are considered the most abundant repeat motif found in eukaryotic proteins. AR domains are predominantly known to mediate specific protein–protein interactions (PPIs) without necessarily recognizing specific primary sequences, nor requiring strict conformity within its own primary sequence. This promiscuity allows for one AR domain to recognize and bind to a variety of intracellular substrates, suggesting that AR-containing proteins may be involved in a wide array of functions. Many AR-containing proteins serve a critical role in biological processes including the ubiquitylation signaling pathway (USP). There is also strong evidence that AR-containing protein malfunction are associated with several neurological diseases and disorders. In this review, the structure and mechanism of key AR-containing proteins are discussed to suggest and/or identify how each protein utilizes their AR domains to support ubiquitylation and the cascading pathways that follow upon substrate modification.

Small-Molecule Gankyrin Inhibition as a Therapeutic Strategy for Breast and Lung Cancer

“…Previous reports have suggested that ankyrin repeat-containing proteins undergo a two-state folding transition, where they show a double sigmoidal-type thermal denaturation curve using CD. − To see if this phenomenon holds true for gankyrin, we performed CD thermal denaturation experiments to characterize the structural stability of gankyrin in the presence and absence of our compounds. As shown in Figure B, we observed that gankyrin does in fact display a two-state folding transition similar to other ankyrin repeat-containing proteins.…”

“…We postulate that some of the α-helical content in gankyrin is still maintained due to increased interactions of critical residues found within gankyrin. This includes the canonical GxTPLHAA motif found in naturally occurring ankyrin repeats that require specific H-bonding and hydrophobic interactions to maintain its characteristic 90° L-shape solenoid fold . The presence of these compounds may be altering the packing and/or proximity of these important residues within gankyrin, limiting its capability to maintain its native fold.…”

“…This includes the canonical GxTPLHAA motif found in naturally occurring ankyrin repeats that require specific H-bonding and hydrophobic interactions to maintain its characteristic 90°L-shape solenoid fold. 39 The presence of these compounds may be altering the packing and/ or proximity of these important residues within gankyrin, limiting its capability to maintain its native fold. Previous reports have suggested that ankyrin repeatcontaining proteins undergo a two-state folding transition, where they show a double sigmoidal-type thermal denaturation curve using CD.…”

ANKFN1 plays both protumorigenic and metastatic roles in hepatocellular carcinoma

“…AR domains were first discovered as a repeating sequence in Saccharomyces cerevisiae cell cycle regulator Swi6 and cell division control protein 10 (Cdc10) and Notch in Drosophila melanogaster [10]. AR domains act as scaffolds to facilitate protein-protein interactions in the cell [11,12] and are present in many eukaryotic proteins, making this domain potentially the most abundant repeat domain in the eukaryotic proteome [13]. FN3 is a very common constituent of animal proteins [14] and has been proven to be an established scaffold for developing nonantibody binding domains [15], which change the conformation of FN3 and eventually translate into structural changes across the membrane [12].…”

Orientia tsutsugamushi Nucleomodulin Ank13 Exploits the RaDAR Nuclear Import Pathway To Modulate Host Cell Transcription

“…The 30- to 33-residue ankyrin repeat (AR) is one of the most common protein-protein interaction motifs in nature and a ubiquitous structural motif across the tree of life ( 24 , 25 ). Analysis of more than 1,900 bacterial species revealed that obligate intracellular bacteria have the highest percentage of AR-containing proteins (Anks) within their proteomes, reflective of their prominence as interfaces with eukaryotic processes ( 24 ).…”