Open AccessFNR‐mediated regulation of hyp expression in Escherichia coli
Author(s) -
Messenger Sarah L.,
Green Jeffrey
Publication year - 2003
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/s0378-1097(03)00726-2
Subject(s) - operon , escherichia coli , promoter , lac operon , biology , transcription (linguistics) , gene , microbiology and biotechnology , transcription factor , coding region , biochemistry , chemistry , gene expression , linguistics , philosophy
The hypA‐E operon is involved in the maturation of all three NiFe hydrogenases in Escherichia coli . Two hyp promoters have been described; a σ 54 ‐dependent promoter upstream of hypA , and a σ 70 ‐dependent promoter (P hypA ) within the hypA coding region. Here it is shown that the oxygen‐responsive transcription factor FNR regulates P hypA under anaerobic conditions only. P hypA does not possess a canonical FNR recognition sequence, but two FNR half‐sites are present. Studies using P hypA :: lacZ fusions carrying lesions in one or both FNR half‐sites indicated that although some residual anaerobic activity was retained by the promoter containing only the downstream FNR half‐site, both half‐sites are required for maximal P hypA activity in vivo. In vitro gel retardation analysis suggested that the primary interaction occurs at the downstream FNR half‐site. Possible explanations for these observations and the implications for other FNR‐regulated promoters are discussed.