Pyrodictium abyssi AbpX reveals a calcium-responsive family of microbial biomatrix proteins that form thermostable hydrogels

• 成果类型: Article
• 署名作者: Sleutel, Mike; Sogues, Adria; Gonzalez Socorro, Andres; Cooman, Vita; Fislage, Marcus; Nijhawan, Adam K.; Zuo, Xiaobing; Alva, Vikram; Remaut, Han; Conticello, Vincent P.
• 署名单位: Vrije Universiteit Brussel; Vrije Universiteit Brussel; Flanders Institute for Biotechnology (VIB); Emory University; United States Department of Energy (DOE); Argonne National Laboratory; Emory University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2600204123
• 发表日期: 2026-06-23
• 页码: e2600204123
• 关键词: biofilms; metal coordination; cryoEM; protein lattice; hydrogelation; DONOR STRAND COMPLEMENTATION; f-actin; pilus; STABILITY; subunit; architecture; polymorphism; TROPOMYOSIN; ARCHAEON; state

摘要

Evolutionary pressure on microbial communities propagating under extreme environmental conditions often results in unique structural adaptations to promote cell survival. Here, we report an investigation of AbpX, a biomatrix protein identified in cultures of the hyperthermophilic archaeon Pyrodictium abyssi. Under ex vivo and in vitro conditions, AbpX assembles into a paracrystalline lattice composed of semiflexible fibrils. CryoEM analysis of recombinant AbpX fibrils reveals that the precursor protein polymerizes through donor strand complementation (DSC), a process previously reported for chaperone-usher fimbriae in Gram-negative bacteria. Unlike the latter DSC protein polymers, AbpX undergoes chaperone-free polymerization in the presence of calcium ions, which are sequestered at the donor strand-acceptor groove interface between protomers in the fibril. Using a combination of cryoEM and crystallographic information, a structural model is proposed for the AbpX lattice that provides insight into its potential role in biofilm formation. These findings suggest that calcium ion coordination may contribute to fibril assembly and preorganize fibrils for incorporation into the protein lattice. Bioinformatic analysis indicates that AbpX exemplifies a distinct and broadly distributed clade of calcium ion responsive biomatrix proteins within the TasA superfamily that can be fabricated into hydrogel biomaterials in vitro under environmentally benign conditions.