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Mechanisms of amphibian arrestin 1 self-association and dynamic distribution in retinal photoreceptors

ABSTRACT: Visual arrestin 1 (Arr1) is an essential protein for termination of the light response in photoreceptors. While mammalian Arr1s form dimers and tetramers at physiological concentrations in vitro, oligomerization in other vertebrates has not been studied. We examined self-association of African clawed frog, Xenopus laevis (xArr1), and salamander, Ambystoma tigrinum (salArr1) Arr1. Sedimentation velocity analytical ultracentrifugation (AUC) showed that xArr1 and salArr1 oligomerization is limited to dimers. The KD for dimer formation was 53 µM for xArr1 and 44 µM for salArr1, similar to the 69 M KD for bovine Arr1 (bArr1) dimers. Mutations of orthologous amino acids important for mammalian Arr1 oligomerization had no impact on xArr1 dimerization. Crystal structure analysis showed that the fold of xArr1 closely resembles that of bArr1. Two xArr1 crystal structures in different space groups revealed two potential xArr1 dimer forms: a dimer with symmetrical packing interfaces from the C-domains of two monomers (CC dimer), similar to that previously predicted from the bArr1 solution structure and a previously observed dimer stabilized by contacts from the N-domain from one monomer and the C-domain from the opposite monomer (CN dimer), and revealed an interdomain rotation in xArr1 dimers that may explain the absence of tetramers. Mutagenesis of residues predicted to interact in either of the two dimer forms yielded modest reduction in dimer affinity, suggesting that the dimer interfaces compete or are not unique. SAXS shows the solution dimer differs from all previous dimers, supporting this conclusion. Finally, a computational model evaluating xArr1 binding to compartment-specific partners and partitioning based on heterogeneity of available cytoplasmic spaces shows that the majority of Arr1 distribution in dark adapted photoreceptors is explained by the excluded volume effect.

ORGANISM(S): Xenopus

SUBMITTER: Bruce Knutson

PROVIDER: PXD056261 | JPOST Repository | Fri Sep 26 00:00:00 BST 2025

REPOSITORIES: jPOST

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Project description:Trypanosoma brucei subspecies infect humans and animals in sub-Saharan Africa. This early diverging eukaryote shows many novel features in basic biological processes, including the use of polycistronic transcription to generate all protein-coding mRNAs. Therefore we hypothesized that translational control provides a means to tune gene expression during parasite development in mammalian and fly hosts. We used ribosome profiling to examine genome-wide protein production in animal-derived slender bloodstream forms and cultured procyclic (insect midgut) forms. About one-third of all CDSs showed statistically significant regulation of protein production between the two stages. Of these, more than two-thirds showed a change in translation efficiency, but few were controlled by this parameter alone. Ribosomal proteins were translated poorly, especially in animal-derived parasites. A disproportionate number of metabolic enzymes were up-regulated at the mRNA level in procyclic forms, as were variant surface glycoproteins in bloodstream forms. Comparison with cultured bloodstream forms from another strain identified stage-specific changes in protein production that transcend strain and growth conditions. Genes with upstream ORFs had a lower mean translation efficiency but no evidence was seen for involvement of these ORFs in stage-regulation. Ribosome profiling revealed that differences in the production of specific proteins in T. brucei slender bloodstream and procyclic forms are more common than anticipated from analysis of mRNA abundance. While in vivo and in vitro derived slender bloodstream forms of different strains are more similar to one another than to procyclic forms, they showed numerous differences at both the mRNA and protein production level. Ribosome profiling and mRNA libraries were constructed in triplicate from in vitro PCF and in vivo BF lifestages of theT. brucei Treu927 and in vitro T. brucei Lister427, to evaluate role of translational gene regulation

			Action	DRS
	20220217_BK_PC_1a.raw	Raw
	20220217_BK_PC_2.raw	Raw
	20220217_BK_PC_3.raw	Raw
	20220217_BK_PC_4.raw	Raw
	Arr1%20PP.xlsx	Xlsx

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Mechanisms of amphibian arrestin 1 self-association and dynamic distribution in retinal photoreceptors

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