Functional significance of the conserved C-Terminal VFVNFA motif in the retina-specific ABC transporter, ABCA4, and its role in inherited visual disease

Patel, Meera J.; Biswas, Subhasis B.; Biswas-Fiss, Esther E.

doi:10.1016/j.bbrc.2019.08.121

Cited by 11 publications

(7 citation statements)

References 27 publications

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“…It may be due to the difference in resolution in this region or an inherent structural difference between these transporters. In our structure, the resolution of the RD domains was low, and accordingly, we used the model generated by Liu et al 25 The highly conserved VFVNFA motif within RD2 interacts with NBD1 as revealed in the structure of ABCA4 25 and in fluorescence resonance energy transfer studies of these domains expressed in bacteria 39 . Earlier mutagenesis studies implicated the C-terminal segment of ABCA4 including the VFVNFA motif in the proper protein folding and function 40 .…”

Section: Purification and Functional Characterization Of Abca4mentioning

confidence: 99%

Cryo-EM structures of the ABCA4 importer reveal mechanisms underlying substrate binding and Stargardt disease

et al. 2021

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ABCA4 is an ATP-binding cassette (ABC) transporter that flips N-retinylidene-phosphatidylethanolamine (N-Ret-PE) from the lumen to the cytoplasmic leaflet of photoreceptor membranes. Loss-of-function mutations cause Stargardt disease (STGD1), a macular dystrophy associated with severe vision loss. To define the mechanisms underlying substrate binding and STGD1, we determine the cryo-EM structure of ABCA4 in its substrate-free and bound states. The two structures are similar and delineate an elongated protein with the two transmembrane domains (TMD) forming an outward facing conformation, extended and twisted exocytoplasmic domains (ECD), and closely opposed nucleotide binding domains. N-Ret-PE is wedged between the two TMDs and a loop from ECD1 within the lumen leaflet consistent with a lateral access mechanism and is stabilized through hydrophobic and ionic interactions with residues from the TMDs and ECDs. Our studies provide a framework for further elucidating the molecular mechanism associated with lipid transport and disease and developing promising disease interventions.

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Section: Purification and Functional Characterization Of Abca4mentioning

confidence: 99%

Cryo-EM structures of the ABCA4 importer reveal mechanisms underlying substrate binding and Stargardt disease

et al. 2021

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“…A search on PubMed and Web of Science for the years 2019–2020 shows dozens of works in which TNP-ATP was used to study ATP-interacting proteins, using both its fluorescence and its characteristic high affinity. Some of these were discussed above; additional examples listed below show the clever and diverse ways TNP-ATP is being used: Determining K d (or K 0.5 ) for multiple nucleotides (i.e., ATP, ADP, AMP, and TNP-ATP) with several known nucleotide binding proteins, including VNUT (see Table 1 ) ( 47 ), ABCF3 (see Table 4 ) ( 74 ), and ABCA4 ( 149 ). Determining differences in binding of TNP-ATP to wild-type and mutant proteins including Rad51 (a human DNA binding protein ( 150 )), SaUspA (a stress-sensing protein from Sulfolobus acidocaldarius , see Table 4 ( 79 )), and Cek1 (a MAP kinase from Candida albicans ( 151 )).…”

Section: Introductionmentioning

confidence: 99%

“…Determining K d (or K 0.5 ) for multiple nucleotides (i.e., ATP, ADP, AMP, and TNP-ATP) with several known nucleotide binding proteins, including VNUT (see Table 1 ) ( 47 ), ABCF3 (see Table 4 ) ( 74 ), and ABCA4 ( 149 ).…”

Section: Introductionmentioning

confidence: 99%

A review of TNP-ATP in protein binding studies: benefits and pitfalls

Woodbury

Whitt²,

Coffman

2021

Biophysical Reports

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“…The ABCA4 c.4601del, p.(Leu1534fs) is predicted to lead to premature termination of translation. As far as we are aware, this variant has not been described in the literature; however, other ABCA4 variants predicted to cause premature termination of translation have been detected in individuals with macular dystrophy [ 30 , 31 ].The consequences of this variant cannot be confirmed without supporting in vitro data; however, we can hypothesise that harbouring this additional variant may explain the intrafamilial phenotypic variability and possible earlier onset of pathology in this patient, especially as the VFVNFA motif in the ABCA4 amino acid sequence is phylogenetically highly conserved [ 32 ]. There is no prior evidence in the literature, to our knowledge, of simultaneous mutations in the TIMP3 and ABCA4 genes.…”

Section: Discussionmentioning

confidence: 99%

Potential CRISPR Base Editing Therapeutic Options in a Sorsby Fundus Dystrophy Patient

Elsayed

Kaukonen

Király

et al. 2022

Genes

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TIMP3 mutations are associated with early-onset macular choroidal neovascularisation for which no treatment currently exists. CRISPR base editing, with its ability to irreversibly correct point mutations by chemical modification of nucleobases at DNA level, may be a therapeutic option. We report a bioinformatic analysis of potential therapeutic options in a patient presenting with Sorsby fundus dystrophy. Genetic testing in a 35-year-old gentleman with bilateral macular choroidal neovascularisation revealed the patient to be heterozygous for a TIMP3 variant c.610A>T, p.(Ser204Cys). Using a glycosylase base editor (GBE), another DNA-edit could be introduced that would revert the variant back to wild-type on amino acid level. Alternatively, the mutated residue could be changed to another amino acid that would be better tolerated, and for that, an available ‘NG’-PAM site was found to be available for the SpCas9-based adenine base editor (ABE) that would introduce p.(Ser204Arg). In silico analyses predicted this variant to be non-pathogenic; however, a bystander edit, p.Ile205Thr, would be introduced. This case report highlights the importance of considering genetic testing in young patients with choroidal neovascularisation, particularly within the context of a strong family history of presumed wet age-related macular degeneration, and describes potential therapeutic options.

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Functional significance of the conserved C-Terminal VFVNFA motif in the retina-specific ABC transporter, ABCA4, and its role in inherited visual disease

Cited by 11 publications

References 27 publications

Cryo-EM structures of the ABCA4 importer reveal mechanisms underlying substrate binding and Stargardt disease

Cryo-EM structures of the ABCA4 importer reveal mechanisms underlying substrate binding and Stargardt disease

A review of TNP-ATP in protein binding studies: benefits and pitfalls

Potential CRISPR Base Editing Therapeutic Options in a Sorsby Fundus Dystrophy Patient

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