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Figure 4 | BMC Evolutionary Biology

Figure 4

From: Evolution and thermodynamics of the slow unfolding of hyperstable monomeric proteins

Figure 4

Characteristics of RNases H. (A-C) Pie diagrams representing the fraction of hydrophobic, polar, and charged residues in the interior of the tertiary structure of hyperstable RNases H. (A) Tt-RNase HI. (B) Sto-RNase HI. (C) Tk-RNase HII. Blue denotes positively charged residues (Arg and Lys). Red denotes negatively charged residues (Asp and Glu). Green denotes polar residues (Asn, Gln, Ser, and Thr). Yellow denotes hydrophobic residues (Ile, Leu, Met, Phe, Trp, Tyr, and Val). White denotes other residues (Ala, Cys, Gly, His, and Pro). Amino-acid residues with relative solvent accessibility greater than 25% were regarded as residues exposed to solvent [67]. (D and E) Amino acid sequence alignments of hyperstable RNases H. (D) RNases HI. (E) RNases HII. Buried residues (Tt, Sto and Tk) and hydrophobic residues are shown in gray and red, respectively. Crosses indicate buried hydrophobic residues in Sto-RNase HI and Tk-RNase HII with non-buried or non-hydrophobic counterpart in Tt-RNase HI and Aa/Tm-RNases HII, respectively. Minuses indicate buried hydrophobic residues in Tt-RNase HI with non-buried or non-hydrophobic counterpart in Sto-RNase HI. (F-H) Crystal structures of hyperstable RNases H. (F) Tt-RNase HI. (G) Sto-RNase HI. (H) Tk-RNase HII. Buried hydrophobic side-chains (relative solvent accessibility less than 25%) are represented by sphere (blue and red). The buried hydrophobic residues in Sto-RNase HI and Tk-RNase HII with nonburied or nonhydrophobic counterpart in Tt-RNase HI and Aa/Tm-RNases HII are shown in red. The figures were created by PyMOL [68].

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