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Göteborgs universitets publikationer

Alkaline pH Is a Signal for Optimal Production and Secretion of the Heat Labile Toxin, LT in Enterotoxigenic Escherichia Coli (ETEC).

Författare och institution:
Lucia Gonzales (Institutionen för biomedicin, avdelningen för mikrobiologi och immunologi); Zahra Bagher Ali (Institutionen för biomedicin, avdelningen för mikrobiologi och immunologi); Erik Nygren (Institutionen för biomedicin, avdelningen för mikrobiologi och immunologi); Zhiyun Wang (-); Stefan Karlsson (Institutionen för biomedicin, avdelningen för mikrobiologi och immunologi); Baoli Zhu (-); Marianne Quiding-Järbrink (Institutionen för biomedicin, avdelningen för mikrobiologi och immunologi); Åsa Sjöling (Institutionen för biomedicin, avdelningen för mikrobiologi och immunologi)
Publicerad i:
PloS one, 8 ( 9 ) s. e74069
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
Enterotoxigenic Escherichia coli (ETEC) cause secretory diarrhea in children and travelers to endemic areas. ETEC spreads through the fecal-oral route. After ingestion, ETEC passes through the stomach and duodenum before it colonizes the lower part of the small intestine, exposing bacteria to a wide range of pH and environmental conditions. This study aimed to determine the impact of external pH and activity of the Cyclic AMP receptor protein (CRP) on the regulation of production and secretion of heat labile (LT) enterotoxin. ETEC strain E2863wt and its isogenic mutant E2863ΔCRP were grown in LBK media buffered to pH 5, 7 and 9. GM1 ELISA, cDNA and cAMP analyses were carried out on bacterial pellet and supernatant samples derived from 3 and 5 hours growth and from overnight cultures. We confirm that CRP is a repressor of LT transcription and production as has been shown before but we show for the first time that CRP is a positive regulator of LT secretion both in vitro and in vivo. LT secretion increased at neutral to alkaline pH compared to acidic pH 5 where secretion was completely inhibited. At pH 9 secretion of LT was optimal resulting in 600 percent increase of secreted LT compared to unbuffered LBK media. This effect was not due to membrane leakage since the bacteria were viable at pH 9. The results indicate that the transition to the alkaline duodenum and/or exposure to high pH close to the epithelium as well as activation of the global transcription factor CRP are signals that induce secretion of the LT toxin in ETEC.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Medicinska grundvetenskaper ->
Mikrobiologi inom det medicinska området ->
Mikrobiologi ->
Medicinsk mikrobiologi
Postens nummer:
Posten skapad:
2013-12-10 13:51

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