3D structures of proteins with coordinated Mn2+ ions from bacteria with low, average, and high genomic GC-content have been\nanalyzed (149 PDB files were used).MajorMn2+ binders are aspartic acid (6.82% ofAsp residues), histidine (14.76% ofHis residues),\nand glutamic acid (3.51% of Glu residues).We found out that the motif of secondary structure ââ?¬Å?beta strand-major binder-random\ncoilââ?¬Â is overrepresented around all the three major Mn2+ binders. That motif may be followed by either alpha helix or beta strand.\nBeta strands nearMn2+ binding residues should be stable because they are enriched by such beta formers as valine and isoleucine,\nas well as by specific combinations of hydrophobic and hydrophilic amino acid residues characteristic to beta sheet. In the group of\nproteins from GC-rich bacteria glutamic acid residues situated in alpha helices frequently coordinateMn2+ ions, probably, because\nof the decrease of Lys usage under the influence of mutational GC-pressure. On the other hand, the percentage of Mn2+ sites with\nat least one amino acid in the ââ?¬Å?beta strand-major binder-random coilââ?¬Â motif of secondary structure (77.88%) does not depend on\ngenomic GC-content.
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