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HoxA is a transcriptional regulator for expression of the hup structural genes in free‐living Bradyrhizobium japonicum
Author(s) -
Van Soom C.,
De Wilde P.,
Vanderleyden J.
Publication year - 1997
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1997.2781648.x
Subject(s) - biology , bradyrhizobium japonicum , hydrogenase , mutant , maltose binding protein , gene , fusion protein , regulator , structural gene , microbiology and biotechnology , promoter , regulation of gene expression , biochemistry , gene expression , genetics , enzyme , bacteria , rhizobiaceae , recombinant dna , symbiosis
A chromosomally integrated Bradyrhizobium japonicum hoxA mutant is unable to oxidize hydrogen in free‐living conditions. Derepressing conditions that induce hydrogenase activity in free‐living, wild‐type B. japonicum cells cannot induce expression of the hydrogenase structural genes in the hoxA mutant. The DNA‐binding capacity of HoxA at the hup promoter region was studied by means of gel retardation. Both heterotrophically growing cells and cells induced to express hydrogenase activity contain a protein that specifically binds to the hup promoter region. Crude protein extracts isolated from a B. japonicum hoxA mutant do not contain this binding compound. The HoxA protein was overexpressed in E. coli and isolated in the form of a maltose‐binding protein (MBP)–HoxA fusion. The MBP–HoxA hybrid protein specifically bound to a 50 bp region of the hupSL promoter known to be important for regulation of hupSL expression.