abstract

• An aprE mutant from B. subtilis 168 lacking the connecting loop Leu 75 - Leu 82 which is predicted to encode a Ca 2 binding site was constructed. Expression of the mutant gene (aprE Δ L e u 75 - L e u 82) produced B. subtilis colonies lacking protease activity. Intrinsic fluorescence analysis revealed spectral differences between wild-type AprE and AprE Δ L 75 - L 82. An AprE Δ L 75 - L 82 variant with reestablished enzyme activity was selected by directed evolution. The novel mutations Thr 66 Met/ Gly 102 Asp located in positions which are predicted to be important for catalytic activity were identified in this variant. Although these mutations restored hydrolysis, they had no effect with respect to thermal inactivation of AprE Δ L 75 - L 82 T 66 M G 102 D. These results support the proposal that in addition to function as a calcium binding site, the loop that connects -sheet e3 with -helix c plays a structural role on enzyme activity of AprE from B. subtilis 168. Copyright © 2009 Eliel R. Romero-Garćia et al.
• An aprE mutant from B. subtilis 168 lacking the connecting loop Leu 75 - Leu 82 which is predicted to encode a Ca 2 %2b binding site was constructed. Expression of the mutant gene (aprE Δ L e u 75 - L e u 82) produced B. subtilis colonies lacking protease activity. Intrinsic fluorescence analysis revealed spectral differences between wild-type AprE and AprE Δ L 75 - L 82. An AprE Δ L 75 - L 82 variant with reestablished enzyme activity was selected by directed evolution. The novel mutations Thr 66 Met/ Gly 102 Asp located in positions which are predicted to be important for catalytic activity were identified in this variant. Although these mutations restored hydrolysis, they had no effect with respect to thermal inactivation of AprE Δ L 75 - L 82 T 66 M G 102 D. These results support the proposal that in addition to function as a calcium binding site, the loop that connects -sheet e3 with -helix c plays a structural role on enzyme activity of AprE from B. subtilis 168. Copyright © 2009 Eliel R. Romero-Garćia et al.

authors

• García-Soto J.
• Nájera H.
• Pedraza-Reyes M.
• Rojo-Domínguez A.
• Romero-García E.R.
• Sampedro Pérez José Guadalupe
• Trujillo M.F.
• Téllez-Valencia A.

publication date

• 2009-01-01

published in

• Journal of Biomedicine and Biotechnology  Journal

keywords

• bacterial protein; calcium ion; glycine; leucine; methionine; protein apre; threonine; unclassified drug; AprE protein, Bacteria; calcium; carrier protein; article; Bacillus subtilis; bacterial strain; bacterium colony; binding site; calcium binding; catalysis; controlled study; enzyme activity; fluorescence analysis; gene expression; nonhuman; protein hydrolysis; chemical structure; chemistry; directed molecular evolution; enzyme stability; enzymology; genetics; kinetics; metabolism; methodology; protein folding; site directed mutagenesis; spectrofluorometry; structure activity relation; Bacillus subtilis; Bacterial Proteins; Binding Sites; Calcium; Directed Molecular Evolution; Enzyme Stability; Kinetics; Membrane Transport Proteins; Models, Molecular; Mutagenesis, Site-Directed; Protein Folding; Spectrometry, Fluorescence; Structure-Activity Relationship

Digital Object Identifier (DOI)

• 10.1155/2009/201075

PubMed ID

• 19710937

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volume

• 2009