Regulation of a Glycerol-Induced Quinoprotein Alcohol Dehydrogenase by σ54 and a LuxR-Type Regulator in Azospirillum brasilense Sp7.
J Bacteriol
; 199(13)2017 07 01.
Article
en En
| MEDLINE
| ID: mdl-28439037
ABSTRACT
Azospirillum brasilense Sp7 uses glycerol as a carbon source for growth and nitrogen fixation. When grown in medium containing glycerol as a source of carbon, it upregulates the expression of a protein which was identified as quinoprotein alcohol dehydrogenase (ExaA). Inactivation of exaA adversely affects the growth of A. brasilense on glycerol. A determination of the transcription start site of exaA revealed an RpoN-dependent -12/-24 promoter consensus. The expression of an exaAlacZ fusion was induced maximally by glycerol and was dependent on σ54 Bioinformatic analysis of the sequence flanking the -12/-24 promoter revealed a 17-bp sequence motif with a dyad symmetry of 6 nucleotides upstream of the promoter, the disruption of which caused a drastic reduction in promoter activity. The electrophoretic mobility of a DNA fragment containing the 17-bp sequence motif was retarded by purified EraR, a LuxR-type transcription regulator that is transcribed divergently from exaA EraR also showed a positive interaction with RpoN in two-hybrid and pulldown assays.IMPORTANCE Quinoprotein alcohol dehydrogenase (ExaA) plays an important role in the catabolism of alcohols in bacteria. Although exaA expression is thought to be regulated by a two-component system consisting of EraS and EraR, the mechanism of regulation was not known. This study shows the details of the regulation of expression of the exaA gene in A. brasilense We have shown here that exaA of A. brasilense is maximally induced by glycerol and harbors a σ54-dependent promoter. The response regulator EraR binds to an inverted repeat located upstream of the exaA promoter. This study shows that a LuxR-type response regulator (EraR) binds upstream of the exaA gene and physically interacts with σ54 The unique feature of this regulation is that EraR is a LuxR-type transcription regulator that lacks the GAFTGA motif, a characteristic feature of the enhancer binding proteins that are known to interact with σ54 in other bacteria.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Proteínas Represoras
/
ARN Polimerasas Dirigidas por ADN
/
Azospirillum brasilense
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Regulación Bacteriana de la Expresión Génica
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Transactivadores
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Oxidorreductasas de Alcohol
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Glicerol
Tipo de estudio:
Prognostic_studies
País/Región como asunto:
America do sul
/
Brasil
Idioma:
En
Revista:
J Bacteriol
Año:
2017
Tipo del documento:
Article
País de afiliación:
India