arc-dependent thermal regulation and extragenic suppression of the Escherichia coli cytochrome d operon

Abstract

DNA sequencing analyses showed that the mini-TnlO insertion resides in the cydB gene, the distal gene of the cydAB operon (cytochrome d). The Ts-growth phenotype was also shown to be associated with previously described cyd alleles. In addition, all cyd mutants were found to be extremely sensitive to hydrogen peroxide.Northern (RNA) blot analysis showed that cyd-specific mRNA levels accumulate following a shift to high temperature. Interestingly, this heat shock induction of the cyd operon was not affected in an rpoHA background but was totally absent in an arcA or arcB mutant background. Extragenic suppressors of the Cyd Ts-phenotype are found at _10-3. Two extragenic suppressors were shown to be null alleles in either arcA or arcB. One interpretation of our results is that in the absence of ArcA or ArcB, which are required for the repression of the cyo operon (cytochrome o), elevated levels of Cyo are produced, thus compensating for the missing cytochrome d function. Consistent with this interpretation, the presence of the cyo gene on a multicopy

Isolation and characterization of an Escherichia coli mutant defective in resuming growth after starvation.

“…This tiny colony phenotype was not seen when exponentially growing AcydAB-l::kan cells were plated at 37~ indicating that, similar to surB1, the temperature-sensitive defect caused by hcydAB-l::kan is specific for exiting stationary phase. Our result differs from the phenotype described previously by Wall et al {1992}, who found that exponential growth of cydAB-mutants was impaired at high temperature. The different phenotypes observed may be the result of the different growth media used or to differences in strain background, or both.…”

“…The surB gene mapped very near a previously described gene, cydC, the function of which is required for the formation of functional cytochrome d oxidase, but which is unlinked to the structural genes for the enzyme cydAB (Georgiou et al 1987;Calhoun et al 1991 (Poole et al 1989;Wall et al 1992}. The parental strain ZK126 grew on minimal glycerol medium in the presence or absence of 150 p.M ZnSO4, but neither the surB1 mutant nor a known ~cydAB mutant was able to grow on minimal glycerol medium containing Zn ~ § All of the strains were able to grow on minimal glucose medium containing 150 ~ra ZnSO4, showing that failure to grow on minimal glycerol medium with Zn ~ § was not attributable to a general sensitivity to Zn 2 +.…”

“…There are six potential membrane-spanning regions, indicated by boxes in Figure 4. The distribution of charged amino acids indicates that the soluble, hydrophilic regions will be in the cytoplasm (Traxler et al 1993 (1990), Cummings et al (1991), Delaney and Georgopoulos (1992), and Shrader et al (1993). The known or predicted direction of transcription for each gene is indicated with an arrow.…”

Regulation of the aerobic respiratory chain in the facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense

“…E. coli has a bo 3 -type quinol oxidase (SoxM-type) that is utilized for atmospheric oxygen concentrations and a bd-type quinol oxidase (alternative oxidase) that is utilized for limited oxygen tension (Kita et al, 1984a, b). Furthermore, the terminal oxidases protect cells from oxidative stress in the form of H 2 O 2 and paraquat (Lindqvist et al, 2000;Skulachev, 1994;Wall et al, 1992). Rhodobacter sphaeroides has an aa 3 -type cytochrome c oxidase (SoxMtype) for atmospheric oxygen concentration and a cbb 3 -type cytochrome c oxidase (FixN type) for limited oxygen tension.…”

Cytochrome d induction in Escherichia coli growing under unfavorable conditions

“…This effect was totally absent from arcA or arcB mutants [22]. In this context it should be mentioned that, according to recent observation of the Konings' group [23], a shift to high temperature causes a much stronger increase in the H' conductance, than in the Na+ conductance of the bacterial membrane.…”