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Molecular analysis of a microaerobically induced operon required for hydrogenase synthesis in Rhizobium leguminosarum biovar viciae
Author(s) -
Rey Luis,
Murillo Jesus,
Hernando Yolanda,
Hidalgo Elena,
Cabrera Ezequiel,
Imperial Juan,
RuizArgüeso Tomás
Publication year - 1993
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 - 10.1111/j.1365-2958.1993.tb01591.x
Subject(s) - operon , hydrogenase , rhizobium leguminosarum , biology , gene product , escherichia coli , biochemistry , nucleic acid sequence , structural gene , gene , mutant , peptide sequence , microbiology and biotechnology , genetics , enzyme , bacteria , rhizobiaceae , gene expression , symbiosis
Summary The nucleotide sequence (6138 bp) of a microaerobically inducible region ( hup V/VI) from the Rhizobium leguminosarum bv. viciae hydrogenase gene cluster has been determined. Six genes, arranged as a single operon, were identified, and designated hypA, B, F, C, D and E based on the sequence similarities of all of them, except hypF , to genes from the hydrogenase pleiotropic operon ( hyp ) from Escherichia coli. The gene products from hypBFCDE were identified by in vivo expression analysis in E. coli , and their molecular sizes were consistent with those predicted from the nucleotide sequence. Transposon Tn5 insertions into hypB, hypF, hypD and hypE resulted in R. leguminosarum mutants that lacked any hydrogenase activity in symbiosis with peas, but still were able to synthesize the polypeptide for the hydrogenase large subunit. The gene products HypA, HypB, HypF and HypD contained CX 2 C motifs characteristic of metal‐binding proteins. In addition, HypB bore a long histidine‐rich stretch of amino acids near the N‐terminus, suggesting a possible role in nickel binding for this protein. The gene product HypF, which was translationally coupled to HypB, presented two cysteine motifs (CX 2 CX 81 CX 2 C) with a capacity to form zinc finger‐like structures in the N ‐terminal third of the protein. A role in nickel metabolism in relation to hydrogenase synthesis is postulated for proteins HypB and HypF.