scholarly journals Ice-Binding Proteins Associated with an Antarctic Cyanobacterium, Nostoc sp. HG1

2020 ◽  
Vol 87 (2) ◽  
Author(s):  
James A. Raymond ◽  
Michael G. Janech ◽  
Marco Mangiagalli
Keyword(s):  
Amino Acid ◽  
Binding Proteins ◽  
Great Majority ◽  
Outer Cell ◽  
Polar Regions ◽  
Amino Acid Motif ◽  
Sequence Analyses ◽  
Ice Binding ◽  
Outer Cell Membrane ◽  
Genes Encoding

ABSTRACT Ice-binding proteins (IBPs) have been identified in numerous polar algae and bacteria, but so far not in any cyanobacteria, despite the abundance of cyanobacteria in polar regions. We previously reported strong IBP activity associated with an Antarctic Nostoc species. In this study, to identify the proteins responsible, as well as elucidate their origin, we sequenced the DNA of an environmental sample of this species, designated Nostoc sp. HG1, and its bacterial community and attempted to identify IBPs by looking for known IBPs in the metagenome and by looking for novel IBPs by tandem mass spectrometry (MS/MS) proteomics analyses of ice affinity-purified proteins. The metagenome contained over 116 DUF3494-type IBP genes, the most common type of IBP identified so far. One of the IBPs could be confidently assigned to Nostoc, while the others could be attributed to diverse bacteria, which, surprisingly, accounted for the great majority of the metagenome. Recombinant Nostoc IBPs (nIBPs) had strong ice-structuring activities, and their circular dichroism spectra were consistent with the secondary structure of a DUF3494-type IBP. nIBP is unusual in that it is the only IBP identified so far to have a PEP (amino acid motif) C-terminal signal, a signal that has been associated with anchoring to the outer cell membrane. These results suggest that the observed IBP activity of Nostoc sp. HG1 was due to a combination of endogenous and exogenous IBPs. Amino acid and nucleotide sequence analyses of nIBP raise the possibility that it was acquired from a planctomycete. IMPORTANCE The horizontal transfer of genes encoding ice-binding proteins (IBPs), proteins that confer freeze-thaw tolerance, has allowed many microorganisms to expand their ranges into polar regions. One group of microorganisms for which nothing is known about its IBPs is cyanobacteria. In this study, we identified a cyanobacterial IBP and showed that it was likely acquired from another bacterium, probably a planctomycete. We also showed that a consortium of IBP-producing bacteria living with the Nostoc contribute to its IBP activity.

scholarly journals How Do Size and Aggregation of Ice-binding Proteins Control their Ice Nucleation Efficiency

2018 ◽  
Author(s):  
Yuqing Qiu ◽  
Arpa Hudait ◽  
Valeria Molinero
Keyword(s):  
Amino Acid ◽  
Cell Membrane ◽  
Binding Site ◽  
Homogeneous Nucleation ◽  
Binding Proteins ◽  
Nucleation And Growth ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Cold Temperatures ◽  
Ice Binding

Organisms that thrive at cold temperatures have evolved ice-binding proteins to manage the nucleation and growth of ice. Bacterial ice-nucleating proteins (INP) and insect hyperactive antifreeze proteins (AFP) bind ice through the same amino acid motifs, despite their opposite functions. AFPs are generally small, while INPs are long and aggregate in the cell membrane. It is not yet understood to which extent the size and aggregation determine the temperature Thet at which proteins nucleate ice. Here we address this question using molecular simulations and nucleation theory. The simulations indicate that the 2.5 nm long Tm AFP nucleates ice at 2±1 ° C above the homogeneous nucleation temperature. Addition of ice-binding loops to Tm AFP increases Thet until the length of the binding-site becomes ~4 times its width, beyond which Thet plateaus. We calculate that the INP of Ps. syringae, Ps INP, reaches its maximum Thet = -26 ° C when its binding site has 16 ice-binding loops, in excellent agreement with Thet = -25 ±1 ° C measured for an engineered 16-loop fragment of Ps INP. To further increase Thet , the proteins must aggregate. We predict Thet per number of Ps INP in the aggregate, and conclude that assemblies with 34 INP already reach Thet = -2 ° C characteristic of this bacterium. Interestingly, we find that Thet of aggregates is a non-monotonic and strongly varying function of the distance between proteins. We conclude that to achieve maximum freezing efficiency, bacteria must exert exquisite, sub-angstrom control of the distance between INP in their membrane.

scholarly journals The pathogenicity of T cell epitopes on human Goodpasture antigen and its critical amino acid motif

2017 ◽  
Vol 21 (9) ◽  
pp. 2117-2128 ◽  
Author(s):  
Shui-yi Hu ◽  
Qiu-hua Gu ◽  
Jia Wang ◽  
Miao Wang ◽  
Xiao-yu Jia ◽  
...  
Keyword(s):  
Amino Acid ◽  
T Cell ◽  
T Cell Epitopes ◽  
Amino Acid Motif ◽  
Critical Amino Acid ◽  
Goodpasture Antigen

scholarly journals Three distinct anti-allergic drugs, amlexanox, cromolyn and tranilast, bind to S100A12 and S100A13 of the S100 protein family

1999 ◽  
Vol 338 (3) ◽  
pp. 583-589 ◽  
Author(s):  
Tsuyoshi SHISHIBORI ◽  
Yuhta OYAMA ◽  
Osamu MATSUSHITA ◽  
Kayoko YAMASHITA ◽  
Hiromi FURUICHI ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Calcium Binding ◽  
Binding Proteins ◽  
S100 Protein ◽  
Reversed Phase ◽  
Molecular Probes ◽  
Calcium Binding Proteins ◽  
Ige Mediated ◽  
Human And Mouse

To investigate the roles of calcium-binding proteins in degranulation, we used three anti-allergic drugs, amlexanox, cromolyn and tranilast, which inhibit IgE-mediated degranulation of mast cells, as molecular probes in affinity chromatography. All of these drugs, which have different structures but similar function, scarcely bound to calmodulin in bovine lung extract, but bound to the same kinds of calcium-binding proteins, such as the 10-kDa proteins isolated in this study, calcyphosine and annexins I–V. The 10-kDa proteins obtained on three drug-coupled resins and on phenyl-Sepharose were analysed by reversed-phase HPLC. It was found that two characteristic 10-kDa proteins, one polar and one less polar, were bound with all three drugs, although S100A2 (S100L), of the S100 family, was bound with phenyl-Sepharose. The cDNA and deduced amino acid sequence proved our major polar protein to be identical with the calcium-binding protein in bovine amniotic fluid (CAAF1, S100A12). The cDNA and deduced amino acid sequence of the less-polar protein shared 95% homology with human and mouse S100A13. In addition, it was demonstrated that the native S100A12 and recombinant S100A12 and S100A13 bind to immobilized amlexanox. On the basis of these findings, we speculate that the three anti-allergic drugs might inhibit degranulation by binding with S100A12 and S100A13.

scholarly journals The Case for Irreversible Binding of Ice-Binding Proteins to Ice

2012 ◽  
Vol 102 (3) ◽  
pp. 461a ◽  
Author(s):  
Ido Braslavsky ◽  
Yeliz Celik ◽  
Ran Drori ◽  
Maya Bar ◽  
Peter L. Davies
Keyword(s):  
Binding Proteins ◽  
Irreversible Binding ◽  
Ice Binding
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