Expression, purification and reconstitution of the 4-hydroxybenzoate transporter PcaK from Acinetobacter sp. ADP1

AbstractThe aromatic acid:H+ symporter family of integral membrane proteins play an important role in the microbial metabolism of aromatic compounds. Here, we show that the 4-hydroxybenzoate transporter from Acinetobacter sp. ADP1, PcaK, can be successfully overexpressed in Escherichia coli and purified by affinity chromatography. Affinity-purified PcaK is a stable, monodisperse homotrimer in the detergent n-dodecyl-β-d-maltopyranoside supplemented with cholesteryl hemisuccinate. The purified protein has α-helical secondary structure and can be reconstituted to a functional state in synthetic proteoliposomes. Asymmetric substrate transport was observed when proteoliposomes were energized by applying an electrochemical proton gradient (Δμ‾H+) or a membrane potential (ΔΨ) but not by ΔpH alone. PcaK was selective in transporting 4-hydroxybenzoate and 3,4-dihydroxybenzoate over closely related compounds, confirming previous reports on substrate specificity. However, PcaK also showed an unexpected preference for transporting 2-hydroxybenzoates. These results provide the basis for further detailed studies of the structure and function of this family of transporters

Noise Pollution and Classroom Acoustics

Noise is a worldwide problem that has negative effects on academic performance. This project, in cooperation with Professor Angel David Cruz Baez from the University of Puerto Rico, evaluated noise levels and sources of noise that were present in San Juan public schools. Through the use of surveys and classroom data collection from four local schools, we determined poor classroom acoustics were problematic in selected schools. From our data and research, we made recommendations to local public schools and the Puerto Rico Department of Education for controlling noise distractions in Puerto Rico public school classrooms. Lastly, we made recommendations to companies located in Puerto Rico for producing acoustical treatments from recyclable materials currently existing on the Island