Membrane-associated activation of cholesterol α-glucosyltransferase, an enzyme responsible for biosynthesis of cholesteryl-α-D-glucopyranoside in Helicobacter pylori critical for its survival.
Helicobacter pylori (H. pylori) is the causative pathogen underlying gastric diseases such as chronic gastritis and gastric cancer. Previously, the authors revealed that α1,4-linked N-acetylglucosamine-capped O-glycan (αGlcNAc) found in gland mucin suppresses H. pylori growth and motility by inhibiting catalytic activity of cholesterol α-glucosyltransferase (CHLαGcT), the enzyme responsible for biosynthesis of the major cell wall component cholesteryl-α-D-glucopyranoside (CGL). Here, the authors developed a polyclonal antibody specific for CHLαGcT and then undertook quantitative ultrastructural analysis of the enzyme's localization in H. pylori. They show that 66.3% of CHLαGcT is detected in the cytoplasm beneath the H. pylori inner membrane, whereas 24.7% is present on the inner membrane. In addition, 2.6%, 5.0%, and 1.4% of the protein were detected in the periplasm, on the outer membrane, and outside microbes, respectively. By using an in vitro CHLαGcT assay with fractionated H. pylori proteins, which were used as an enzyme source for CHLαGcT, the authors demonstrated that the membrane fraction formed CGL, whereas other fractions did not. These data combined together indicate that CHLαGcT is originally synthesized in the cytoplasm of H. pylori as an inactive form and then activated when it is associated with the cell membrane. This article contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
Hoshino
Hitomi
H
Department of Pathology, Shinshu University School of Medicine, Matsumoto, Japan.
Tsuchida
Akiko
A
Kametani
Kiyokazu
K
Mori
Masako
M
Nishizawa
Tomoko
T
Suzuki
Takefumi
T
Nakamura
Hitomi
H
Lee
Heeseob
H
Ito
Yuki
Y
Kobayashi
Motohiro
M
Masumoto
Junya
J
Fujita
Masaya
M
Fukuda
Minoru
M
Nakayama
Jun
J
D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000031:analogs & derivatives* / Q000096:biosynthesis; D004789:Enzyme Activation; D005964:Glucosyltransferases / Q000032:analysis / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D016480:Helicobacter pylori / Q000166:cytology* / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology; D042541:Intracellular Space / Q000201:enzymology / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D021381:Protein Transport
D000906:Antibodies; C027578:cholesteryl glucoside; D002784:Cholesterol; D005964:Glucosyltransferases; C514935:Hp0421 protein, Helicobacter pylori