Lehrstuhl für Biochemie, Institut für organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany.
Science. 2011 Apr 15;332(6027):352-4. doi: 10.1126/science.1199098.
The formate transporter FocA was described to switch its mode of operation from a passive export channel at high external pH to a secondary active formate/H(+) importer at low pH. The crystal structure of Salmonella typhimurium FocA at pH 4.0 shows that this switch involves a major rearrangement of the amino termini of individual protomers in the pentameric channel. The amino-terminal helices open or block transport in a concerted, cooperative action that indicates how FocA is gated in a pH-dependent way. Electrophysiological studies show that the protein acts as a specific formate channel at pH 7.0 and that it closes upon a shift of pH to 5.1.
高 pH 时，甲酸盐转运蛋白 FocA 作为一个被动的外排通道；低 pH 时，它又切换成一个主动的甲酸盐/H(+)同向转运体。在 pH 值为 4.0 时，沙门氏菌 FocA 的晶体结构显示这种转换涉及到五聚体通道中每个单体氨基酸末端的重大重排。氨基末端螺旋以协同、协作的方式打开或阻断运输，表明 FocA 如何以 pH 依赖的方式进行门控。电生理学研究表明，该蛋白在 pH 值为 7.0 时作为一种特定的甲酸盐通道发挥作用，当 pH 值变为 5.1 时，该通道关闭。
