Ca2+-stabilized adhesin helps an Antarctic bacterium reach out and bind ice
| Autor: | Luuk L. C. Olijve, Peter L. Davies, Ilja K. Voets, Tyler D. R. Vance, Robert L. Campbell, Shuaiqi Guo |
|---|---|
| Přispěvatelé: | Macromolecular and Organic Chemistry, Stimuli-responsive Funct. Materials & Dev., Macro-Organic Chemistry |
| Rok vydání: | 2014 |
| Předmět: |
lcsh:Life
lcsh:QR1-502 Crystal structure Crystallography X-Ray Biochemistry Bacterial cell structure lcsh:Microbiology Protein Structure Secondary Protein structure X-Ray Diffraction TISS type I secretion system solution structure RDF radial distribution function Marinomonas 0303 health sciences biology Small-angle X-ray scattering AFP antifreeze protein SAXS small-angle X-ray scattering bacterial Ig-like fold RIV repetitive Region IV XRD X-ray diffraction Protein Binding crystal structure aa amino acid Biophysics Antarctic Regions Immunoglobulins Ca2+-binding S2 RTX repeats-in-toxin 03 medical and health sciences Bacterial Proteins ORF open reading frame Antifreeze protein Scattering Small Angle Molecular Biology WLC worm-like chain 030304 developmental biology Original Paper Binding Sites AUC analytical ultracentrifugation ice-binding adhesin 030306 microbiology Ice Cell Biology biology.organism_classification Solution structure Protein Structure Tertiary Bacterial adhesin Oxygen MpAFP Marinomonas primoryensis antifreeze protein lcsh:QH501-531 RII Region II Food extender domain RII tetra-tandemer four tandem RII Calcium BIg bacterial immunoglobulin Bacteria |
| Zdroj: | Bioscience Reports Bioscience Reports, Vol 34, Iss 4, p e00121 (2014) Bioscience Reports, 34(4):e00121, 357-368. Portland Press Ltd. |
| ISSN: | 1573-4935 0144-8463 |
| Popis: | The large size of a 1.5-MDa ice-binding adhesin [MpAFP (Marinomonas primoryensis antifreeze protein)] from an Antarctic Gram-negative bacterium, M. primoryensis, is mainly due to its highly repetitive RII (Region II). MpAFP_RII contains roughly 120 tandem copies of an identical 104-residue repeat. We have previously determined that a single RII repeat folds as a Ca2+-dependent immunoglobulin-like domain. Here, we solved the crystal structure of RII tetra-tandemer (four tandem RII repeats) to a resolution of 1.8 Å. The RII tetra-tandemer reveals an extended (~190-Å × ~25-Å), rod-like structure with four RII-repeats aligned in series with each other. The inter-repeat regions of the RII tetra-tandemer are strengthened by Ca2+ bound to acidic residues. SAXS (small-angle X-ray scattering) profiles indicate the RII tetra-tandemer is significantly rigidified upon Ca2+ binding, and that the protein's solution structure is in excellent agreement with its crystal structure. We hypothesize that >600 Ca2+ help rigidify the chain of ~120 104-residue repeats to form a ~0.6 μm rod-like structure in order to project the ice-binding domain of MpAFP away from the bacterial cell surface. The proposed extender role of RII can help the strictly aerobic, motile bacterium bind ice in the upper reaches of the Antarctic lake where oxygen and nutrients are most abundant. Ca2+-induced rigidity of tandem Ig-like repeats in large adhesins might be a general mechanism used by bacteria to bind to their substrates and help colonize specific niches. An Antarctic bacterium, Marinomonas primoryensis, uses a 1.5-MDa adhesin to bind ice. Crystal and solution structures of four of its 120 tandem Ig-like repeats show how Ca2+ rigidifies and projects the adhesin from the bacteria to the ice. |
| Databáze: | OpenAIRE |
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