scholarly journals Aquaporin Z of Escherichia coli: Reassessment of Its Regulation and Physiological Role

2002 ◽  
Vol 184 (15) ◽  
pp. 4304-4307 ◽  
Author(s):  
Eric Soupene ◽  
Natalie King ◽  
Haidy Lee ◽  
Sydney Kustu

ABSTRACT Transcription of an aqpZ-lac fusion in a single copy on the Escherichia coli chromosome increased as cells entered the stationary growth phase. This was true in a variety of media, and increased transcription in enriched medium required the RpoS sigma factor. Expression of the aqpZ-lac fusion was not affected by up- or downshifts in osmolality. Disruption of aqpZ had no detectable adverse effects.

2009 ◽  
Vol 191 (9) ◽  
pp. 3177-3182 ◽  
Author(s):  
Ilana Kolodkin-Gal ◽  
Hanna Engelberg-Kulka

ABSTRACT Escherichia coli mazEF is a toxin-antitoxin gene module that mediates cell death during exponential-phase cellular growth through either reactive oxygen species (ROS)-dependent or ROS-independent pathways. Here, we found that the stationary-phase sigma factor σS was responsible for the resistance to mazEF-mediated cell death during stationary growth phase. Deletion of rpoS, the gene encoding σS from the bacterial chromosome, permitted mazEF-mediated cell death during stationary growth phase.


2003 ◽  
Vol 185 (23) ◽  
pp. 7008-7014 ◽  
Author(s):  
Benchamas Subsin ◽  
Mark S. Thomas ◽  
Gerd Katzenmeier ◽  
Jonathan G. Shaw ◽  
Sumalee Tungpradabkul ◽  
...  

ABSTRACT The Burkholderia pseudomallei rpoS gene was identified, and an rpoS null mutant was constructed. The mutant was shown to have an increased sensitivity to carbon starvation and oxidative stress. By using rpoS-lacZ fusions, transcription of rpoS was shown to be growth phase regulated, reaching a peak upon entry into stationary phase.


2008 ◽  
Vol 74 (15) ◽  
pp. 4847-4852 ◽  
Author(s):  
Anastasia Matthies ◽  
Thomas Clavel ◽  
Michael Gütschow ◽  
Wolfram Engst ◽  
Dirk Haller ◽  
...  

ABSTRACT The metabolism of isoflavones by gut bacteria plays a key role in the availability and bioactivation of these compounds in the intestine. Daidzein and genistein are the most common dietary soy isoflavones. While daidzein conversion yielding equol has been known for some time, the corresponding formation of 5-hydroxy-equol from genistein has not been reported previously. We isolated a strictly anaerobic bacterium (Mt1B8) from the mouse intestine which converted daidzein via dihydrodaidzein to equol as well as genistein via dihydrogenistein to 5-hydroxy-equol. Strain Mt1B8 was a gram-positive, rod-shaped bacterium identified as a member of the Coriobacteriaceae. Strain Mt1B8 also transformed dihydrodaidzein and dihydrogenistein to equol and 5-hydroxy-equol, respectively. The conversion of daidzein, genistein, dihydrodaidzein, and dihydrogenistein in the stationary growth phase depended on preincubation with the corresponding isoflavonoid, indicating enzyme induction. Moreover, dihydrogenistein was transformed even more rapidly in the stationary phase when strain Mt1B8 was grown on either genistein or daidzein. Growing the cells on daidzein also enabled conversion of genistein. This suggests that the same enzymes are involved in the conversion of the two isoflavones.


2010 ◽  
Vol 8 (1) ◽  
pp. 51 ◽  
Author(s):  
Niurka Meneses ◽  
Guillermo Mendoza-Hernández ◽  
Sergio Encarnación

PROTEOMICS ◽  
2018 ◽  
Vol 18 (14) ◽  
pp. 1800116 ◽  
Author(s):  
Micaela Cerletti ◽  
María Ines Giménez ◽  
Christian Tröetschel ◽  
Celeste D’ Alessandro ◽  
Ansgar Poetsch ◽  
...  

1979 ◽  
Vol 42 (11) ◽  
pp. 848-851 ◽  
Author(s):  
Y. PARK ◽  
E. M. MIKOLAJCIK

Growth and alpha toxin production by a strain of Clostridium perfringens was determined in Thioglycollate medium, beef broth with ground beef, and beef broth with ground beef and soy protein. Incubation temperatures ranged from 15 to 50 C. In Thioglycollate medium, maximum alpha toxin production occurred at 35 C and was 40 times greater than that observed at 45 C. However, generation time and maximum population were approximately the same at 35 and 45 C. At 15 C, a two log cycle reduction in viable counts occurred within 6 h. Irrespective of incubation temperature, alpha toxin levels in Thioglycollate medium declined as the incubation period was extended beyond the stationary growth phase. In the beef broth with ground beef system which was studied at 35 C only, the organism grew slower and produced less toxin than in Thioglycollate medium. The amount of alpha toxin detected was influenced to a greater extent by the incubation time and temperature, the holding time beyond the stationary growth phase, and the growth medium than by the population level of C. perfringens.


RNA Biology ◽  
2016 ◽  
Vol 13 (4) ◽  
pp. 427-440 ◽  
Author(s):  
Efthimia Lioliou ◽  
Pierre Fechter ◽  
Isabelle Caldelari ◽  
Brian C. Jester ◽  
Sarah Dubrac ◽  
...  

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