Tetrapyrrole biosynthesis in Rhodobacter capsulatus is transcriptionally regulated by the heme-binding regulatory protein, HbrL.
J Bacteriol
; 188(4): 1567-76, 2006 Feb.
Article
em En
| MEDLINE
| ID: mdl-16452440
ABSTRACT
We demonstrate that the expression of hem genes in Rhodobacter capsulatus is transcriptionally repressed in response to the exogenous addition of heme. A high-copy suppressor screen for regulators of hem gene expression resulted in the identification of an LysR-type transcriptional regulator, called HbrL, that regulates hem promoters in response to the availability of heme. HbrL is shown to activate the expression of hemA and hemZ in the absence of exogenous hemin and repress hemB expression in the presence of exogenous hemin. Heterologously expressed HbrL apoprotein binds heme b and is purified with bound heme b when expressed in the presence of 5-aminolevulinic acid. Electrophoretic gel shift analysis demonstrated that HbrL binds the promoter region of hemA, hemB, and hemZ as well as its own promoter and that the presence of heme increases the binding affinity of HbrL to hemB.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Transcrição Gênica
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Regulação Bacteriana da Expressão Gênica
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Rhodobacter capsulatus
Idioma:
En
Ano de publicação:
2006
Tipo de documento:
Article