scholarly journals Analysis of Transcription of theStaphylococcus aureus Aerobic Class Ib and Anaerobic Class III Ribonucleotide Reductase Genes in Response to Oxygen

2001 ◽  
Vol 183 (24) ◽  
pp. 7260-7272 ◽  
Author(s):  
Mahmud Masalha ◽  
Ilya Borovok ◽  
Rachel Schreiber ◽  
Yair Aharonowitz ◽  
Gerald Cohen
Keyword(s):  
Oxygen Concentration ◽  
Ribonucleotide Reductase ◽  
Transcriptional Response ◽  
Anaerobic Growth ◽  
Class Iii ◽  
Aerobic Conditions ◽  
Repeat Elements ◽  
Facultative Aerobe ◽  
Effect Of Oxygen ◽  
Class Ib

ABSTRACT Staphylococcus aureus is a gram-positive facultative aerobe that can grow in the absence of oxygen by fermentation or by using an alternative electron acceptor. To investigate the mechanism by which S. aureus is able to adapt to changes in oxygen concentration, we analyzed the transcriptional regulation of genes that encode the aerobic class Ib and anaerobic class III ribonucleotide reductase (RNR) systems that are responsible for the synthesis of deoxyribonucleotides needed for DNA synthesis. The S. aureus class Ib RNR nrdIEF and class III RNRnrdDG genes and their regulatory regions were cloned and sequenced. Inactivation of the nrdDG genes showed that the class III RNR is essential for anaerobic growth. Inhibition of aerobic growth by hydroxyurea showed that the class Ib RNR is an oxygen-dependent enzyme. Northern blot analysis and primer extension analysis demonstrated that transcription of class IIInrdDG genes is regulated by oxygen concentration and was at least 10-fold higher under anaerobic than under aerobic conditions. In contrast, no significant effect of oxygen concentration was found on the transcription of class Ib nrdIEF genes. Disruption or deletion of S. aureus nrdDG genes caused up to a fivefold increase in nrdDG and nrdIEFtranscription under anaerobic conditions but not under aerobic conditions. Similarly, hydroxyurea, an inhibitor of the class I RNRs, resulted in increased transcription of class Ib and class III RNR genes under aerobic conditions. These findings establish that transcription of class Ib and class III RNR genes is upregulated under conditions that cause the depletion of deoxyribonucleotide. Promoter analysis of class Ib and class III RNR operons identified several inverted-repeat elements that may account for the transcriptional response of thenrdIEF and nrdDG genes to oxygen.

scholarly journals Staphylococcus aureus NrdH Redoxin Is a Reductant of the Class Ib Ribonucleotide Reductase

2010 ◽  
Vol 192 (19) ◽  
pp. 4963-4972 ◽  
Author(s):  
Inbal Rabinovitch ◽  
Michaela Yanku ◽  
Adva Yeheskel ◽  
Gerald Cohen ◽  
Ilya Borovok ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Ribonucleotide Reductase ◽  
Thioredoxin Reductase ◽  
Reducing Power ◽  
Anaerobic Growth ◽  
Structural Motif ◽  
Thiol Redox ◽  
Class Ib

ABSTRACT Staphylococci contain a class Ib NrdEF ribonucleotide reductase (RNR) that is responsible, under aerobic conditions, for the synthesis of deoxyribonucleotide precursors for DNA synthesis and repair. The genes encoding that RNR are contained in an operon consisting of three genes, nrdIEF, whereas many other class Ib RNR operons contain a fourth gene, nrdH, that determines a thiol redoxin protein, NrdH. We identified a 77-amino-acid open reading frame in Staphylococcus aureus that resembles NrdH proteins. However, S. aureus NrdH differs significantly from the canonical NrdH both in its redox-active site, C-P-P-C instead of C-M/V-Q-C, and in the absence of the C-terminal [WF]SGFRP[DE] structural motif. We show that S. aureus NrdH is a thiol redox protein. It is not essential for aerobic or anaerobic growth and appears to have a marginal role in protection against oxidative stress. In vitro, S. aureus NrdH was found to be an efficient reductant of disulfide bonds in low-molecular-weight substrates and proteins using dithiothreitol as the source of reducing power and an effective reductant for the homologous class Ib RNR employing thioredoxin reductase and NADPH as the source of the reducing power. Its ability to reduce NrdEF is comparable to that of thioredoxin-thioredoxin reductase. Hence, S. aureus contains two alternative thiol redox proteins, NrdH and thioredoxin, with both proteins being able to function in vitro with thioredoxin reductase as the immediate hydrogen donors for the class Ib RNR. It remains to be clarified under which in vivo physiological conditions the two systems are used.

scholarly journals The enzymes of B. coli communis . Part V.—(a) anaerobic growth followed by anaerobic and aerobic fermentation. (b) the effects of aeration during the fermentation

1921 ◽  
Vol 92 (644) ◽  
pp. 135-150
Keyword(s):  
Anaerobic Growth ◽  
Aerobic Growth ◽  
Aerobic Fermentation ◽  
The Subject ◽  
The Difference ◽  
Effect Of Oxygen ◽  
Present Section ◽  
Ferment Glucose

In the present communications the effect of oxygen upon the fermentation of glucose and upon the growth of the bacteria, in so far as this affects fermentation, is considered. To this end the organisms have been grown both aerobically and anaerobically, and subsequently made to ferment glucose, both aerobically and anaerobically, with the object of comparing the products of decomposition in the two cases. There are clearly two problems : firstly, the effect of exposure to oxygen during growth upon the subsequent fermentation, whether aerobic or anaerobic, and, secondly, the effect of oxygen admitted during the fermentation. The first question relates to the part played by oxygen in the formation of enzymes, the second to the part played by oxygen in their action on carbohydrates. The first question is considered, though in but a preliminary way, in Section A, the second, more fully, in Section B. Section A. Object of the Experiments . Two results were aimed at in these experiments. Firstly, to compare the products of fermentation of glucose anaerobically, after anaerobic growth, with the products of fermentation anaerobically after previous growth aerobically. And, secondly, to obtain information as to the effect of introducing oxygen during the fermentation itself. This latter consideration, however, though brought to notice by these experiments, is considered only incidentally here because it forms the subject of Section B. In the present section we wish to direct attention particularly to those differences which exist between the fermentation after anaerobic and aerobic growth, not upon the effect of aeration during the fermentation. To point out the difference which previous growth aerobically or anaerobically has made, several analyses from previous experiments are included in Table IV side by side with the completely anaerobic experiments of Tables I, II, and III.

scholarly journals Effect of Oxygen Concentration on the Detection of Mercury in an Atmospheric Microwave Discharge

1999 ◽  
Vol 38 (Part 1, No. 7B) ◽  
pp. 4595-4600 ◽  
Author(s):  
Kamal Hadidi ◽  
Paul P. Woskov ◽  
Guadalupe J. Flores ◽  
Kareen Green ◽  
Paul Thomas
Keyword(s):  
Oxygen Concentration ◽  
Microwave Discharge ◽  
Effect Of Oxygen
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