H+ゲート型尿素チャネル:ヘリコバクター・ピロリ尿素酵素と胃の植民地化との関連

D L Weeks¹, S Eskandari, D R Scott

¹VA Greater Los Angeles Healthcare System and Department of Physiology, University of California, Los Angeles, CA 90073, USA.

Science (New York, N.Y.)

|January 22, 2000

まとめ

ヘリコバクター・パイロリ菌 (Helicobacter pylori) が感染しています.

科学分野:

微生物学微生物学とは
分子生物学は分子生物学である.
バイオケミストリーバイオケミストリー

背景:

ヘリコバクター・パイロリ (Helicobacter pylori) はヒトの胃病原体である.
酸性環境は,生存に不可欠な細胞質尿素酵素を活性化させます.
ureI遺伝子製品は,この酸性耐性メカニズムに関与しています.

研究の目的:

UREIタンパク質の機能と性質を調査する.
Helicobacter pyloriの酸性耐性におけるUREIの役割を明らかにするために.
酸誘発ウレアース活性化のメカニズムを決定する.

主な方法:

UREI.I.を特徴づけるために,インビトロ転写/翻訳と膜分離を行います.
尿素の吸収を研究するために,Xenopusの卵細胞におけるUreIの発現.
サイト・ディレクテッド・ミュータゲネシス (ヒスティジン123) で,機能的重要性を評価する.
輸送運動の分析 (特異性,飽和度,電生成性,温度依存性).

主要な成果:

UREIは6つのトランスメブランセグメントを持つ内膜タンパク質です.
UREIは,Xenopusの卵細胞における酸刺激による尿素特異的輸送を促進する.
ヒスティジン123の変異は,UREI媒介の酸刺激を無効化する.
UreIは,受動的,不飽和,非電気的,温度に依存しないH+ゲート尿素チャネルとして機能します.

結論:

UREIは,ヘリコバクター・ピロリにおける重要なH+ゲート型尿素チャネルとして機能する.
このチャネルは,酸性条件への反応として,細胞質尿素酵素の活性を調節する.
UREIは,細菌の酸性耐性,胃の生存,そしてコロニー化において重要な役割を果たします.

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