کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5533178 1402105 2017 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Dynamic Phenylalanine Clamp Interactions Define Single-Channel Polypeptide Translocation through the Anthrax Toxin Protective Antigen Channel
ترجمه فارسی عنوان
تعاملات گیره فینیلالانین پویا تعریف انتقال کانال پلیپپتیدی از طریق کانال آنتی ژن حفاظتی سم زدایی آنتارکس
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیولوژی سلول
چکیده انگلیسی


- Small guest/host peptide probes were tested on protective antigen channels.
- Tryptophan containing peptides translocated while oscillating between intermediates.
- The oscillating intermediates were part of the translocation pathway.
- Prenucleated helix peptide translocated poorly through wild-type channels.
- Efficient translocation requires peptide flexibility and dynamic phenylalanine clamp site.

Anthrax toxin is an intracellularly acting toxin where sufficient detail is known about the structure of its channel, allowing for molecular investigations of translocation. The toxin is composed of three proteins, protective antigen (PA), lethal factor (LF), and edema factor (EF). The toxin's translocon, PA, translocates the large enzymes, LF and EF, across the endosomal membrane into the host cell's cytosol. Polypeptide clamps located throughout the PA channel catalyze the translocation of LF and EF. Here, we show that the central peptide clamp, the ϕ clamp, is a dynamic site that governs the overall peptide translocation pathway. Single-channel translocations of a 10-residue, guest-host peptide revealed that there were four states when peptide interacted with the channel. Two of the states had intermediate conductances of 10% and 50% of full conductance. With aromatic guest-host peptides, the 50% conducting intermediate oscillated with the fully blocked state. A Trp guest-host peptide was studied by manipulating its stereochemistry and prenucleating helix formation with a covalent linkage in the place of a hydrogen bond or hydrogen-bond surrogate (HBS). The Trp peptide synthesized with ʟ-amino acids translocated more efficiently than peptides synthesized with D- or alternating D,ʟ-amino acids. HBS stapled Trp peptide exhibited signs of steric hindrance and difficulty translocating. However, when mutant ϕ clamp (F427A) channels were tested, the HBS peptide translocated normally. Overall, peptide translocation is defined by dynamic interactions between the peptide and ϕ clamp. These dynamics require conformational flexibility, such that the peptide productively forms both extended-chain and helical states during translocation.

Graphical Abstract63

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Biology - Volume 429, Issue 6, 24 March 2017, Pages 900-910
نویسندگان
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