Cysteine-rich protein 2 accelerates actin filament cluster formation

• Published in: PloS one 2017-08, Vol.12 (8), p.e0183085-e0183085
• Main Authors: Kihara, Takanori, Sugimoto, Yasunobu, Shinohara, Satoko, Takaoka, Shunpei, Miyake, Jun
• Format: Article
• Language: English
• Subjects: Actin; Actin Cytoskeleton - chemistry; Actin Cytoskeleton - metabolism; Animals; Binding; Biochemical analysis; Bioengineering; Biology and Life Sciences; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Cell migration; Cell morphology; Clustering; Curvature; Cysteine; Cytology; Cytoskeleton; Experiments; Filaments; Gene expression; LIM Domain Proteins - chemistry; LIM Domain Proteins - metabolism; Mice; Models, Molecular; Physical Sciences; Polymerization; Properties; Protein Binding; Protein Conformation; Protein Interaction Domains and Motifs; Protein Multimerization; Protein research; Proteins; Recombinant Proteins; Scattering; Small angle X ray scattering; Smooth muscle; Testing; Transcription factors; α-Actinin
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0183085

Filamentous actin (F-actin) forms many types of structures and dynamically regulates cell morphology and movement, and plays a mechanosensory role for extracellular stimuli. In this study, we determined that the smooth muscle-related transcription factor, cysteine-rich protein 2 (CRP2), regulates the supramolecular networks of F-actin. The structures of CRP2 and F-actin in solution were analyzed by small-angle X-ray solution scattering (SAXS). The general shape of CRP2 was partially unfolded and relatively ellipsoidal in structure, and the apparent cross sectional radius of gyration (Rc) was about 15.8 Å. The predicted shape, derived by ab initio modeling, consisted of roughly four tandem clusters: LIM domains were likely at both ends with the middle clusters being an unfolded linker region. From the SAXS analysis, the Rc of F-actin was about 26.7 Å, and it was independent of CRP2 addition. On the other hand, in the low angle region of the CRP2-bound F-actin scattering, the intensities showed upward curvature with the addition of CRP2, which indicates increasing branching of F-actin following CRP2 binding. From biochemical analysis, the actin filaments were augmented and clustered by the addition of CRP2. This F-actin clustering activity of CRP2 was cooperative with α-actinin. Thus, binding of CRP2 to F-actin accelerates actin polymerization and F-actin cluster formation.