Microbiology ◽  
2006 ◽  
Vol 152 (1) ◽  
pp. 11-21 ◽  
Author(s):  
Mónica Barriuso-Iglesias ◽  
Carlos Barreiro ◽  
Fabio Flechoso ◽  
Juan F. Martín

Corynebacterium glutamicum, a soil Gram-positive bacterium used for industrial amino acid production, was found to grow optimally at pH 7·0–9·0 when incubated in 5 litre fermenters under pH-controlled conditions. The highest biomass was accumulated at pH 9·0. Growth still occurred at pH 9·5 but at a reduced rate. The expression of the pH-regulated F0F1 ATPase operon (containing the eight genes atpBEFHAGDC) was induced at alkaline pH. A 7·5 kb transcript, corresponding to the eight-gene operon, was optimally expressed at pH 9·0. The same occurred with a 1·2 kb transcript corresponding to the atpB gene. RT-PCR studies confirmed the alkaline pH induction of the F0F1 operon and the existence of the atpI gene. The atpI gene, located upstream of the F0F1 operon, was expressed at a lower level than the polycistronic 7·5 kb mRNA, from a separate promoter (P-atp1). Expression of the major promoter of the F0F1 operon, designated P-atp2, and the P-atp1 promoter was quantified by coupling them to the pET2 promoter-probe vector. Both P-atp1 and P-atp2 were functional in C. glutamicum and Escherichia coli. Primer extension analysis identified one transcription start point inside each of the two promoter regions. The P-atp1 promoter fitted the consensus sequence of promoters recognized by the vegetative σ factor of C. glutamicum, whereas the −35 and −10 boxes of P-atp2 fitted the consensus sequence for σ H-recognized Mycobacterium tuberculosis promoters CC/GGGA/GAC 17–22 nt C/GGTTC/G, known to be involved in expression of heat-shock and other stress-response genes. These results suggest that the F0F1 operon is highly expressed at alkaline pH, probably using a σ H RNA polymerase.


Microbiology ◽  
2009 ◽  
Vol 155 (2) ◽  
pp. 594-603 ◽  
Author(s):  
Worrawat Promden ◽  
Alisa S. Vangnai ◽  
Hirohide Toyama ◽  
Kazunobu Matsushita ◽  
Piamsook Pongsawasdi

The transcriptional regulation of three distinct alcohol oxidation systems, alcohol dehydrogenase (ADH)-I, ADH-IIB and ADH-IIG, in Pseudomonas putida HK5 was investigated under various induction conditions. The promoter activities of the genes involved in alcohol oxidation were determined using a transcriptional lacZ fusion promoter-probe vector. Ethanol was the best inducer for the divergent promoters of qedA and qedC, encoding ADH-I and a cytochrome c, respectively. Primary and secondary C3 and C4 alcohols and butyraldehyde specifically induced the divergent promoters of qbdBA and aldA, encoding ADH-IIB and an NAD-dependent aldehyde dehydrogenase, respectively. The qgdA promoter of ADH-IIG responded well to (S)-(+)-1,2-propanediol induction. In addition, the roles of genes encoding the response regulators exaE and agmR, located downstream of qedA, were inferred from the properties of exaE- or agmR-disrupted mutants and gene complementation tests. The gene products of both exaE and agmR were strictly necessary for qedA transcription. The mutation and complementation studies also suggested a role for AgmR, but not ExaE, in the transcriptional regulation of qbdBA (ADH-IIB) and qgdA (AGH-IIG). A hypothetical scheme describing a regulatory network, which directs expression of the three distinct alcohol oxidation systems in P. putida HK5, was derived.


Microbiology ◽  
2002 ◽  
Vol 148 (2) ◽  
pp. 615-623 ◽  
Author(s):  
Jürgen Prell ◽  
Bert Boesten ◽  
Philip Poole ◽  
Ursula B Priefer

A Rhizobium leguminosarum bv. viciae VF39 gene (gabT) encoding a γ-aminobutyrate (GABA) aminotransferase was identified, cloned and characterized. This gene is thought to be involved in GABA metabolism via the GABA shunt pathway, a theoretical bypass of the 2-oxoglutarate dehydrogenase complex. Mutants in gabT are still able to grow on GABA as a sole carbon and nitrogen source. 2-Oxoglutarate-dependent GABA aminotransferase activity is absent in these mutants, while pyruvate-dependent activity remains unaffected. This indicates that at least two enzymes with different substrate specifities are involved in the GABA metabolism of R. leguminosarum bv. viciae VF39. The gabT promoter was cloned into a newly constructed, stable promoter-probe vector pJP2, suitable for the study of transcriptional GUS fusions in free-living bacteria and during symbiosis. Under free-living conditions the gabT promoter is induced by GABA and repressed by succinate. Transcriptional regulation is mediated by GabR in a repressor-like manner. During symbiosis with the pea host plant gabT is induced and highly expressed in the symbiotic zone. Nodules induced by gabT mutants, however, are still effective in nitrogen fixation.


1989 ◽  
Vol 3 (8) ◽  
pp. 1011-1023 ◽  
Author(s):  
S. F. Park ◽  
D. A. Stirling ◽  
C. S. J. Hulton ◽  
I. R. Booth ◽  
C. F. Higgins ◽  
...  

2014 ◽  
Vol 50 (72) ◽  
pp. 10430-10433 ◽  
Author(s):  
Min Ma ◽  
Yanjiu Xue ◽  
Weiying Liu ◽  
Hong Zhang ◽  
Lingyi Kong ◽  
...  

Coupling the deletion of an endogenous gene and a non-integrative promoter-probe vector allowed reliable identification of biosynthetic promoters of nosiheptide.


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