Open AccessCharacterization of two genes ( hupD and hupE ) required for hydrogenase activity in Azotobacter chroococcum
Author(s) -
Du Lisheng,
Stejskal Fran,
Tibelius Karl H.
Publication year - 1992
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 - 10.1111/j.1574-6968.1992.tb05399.x
Subject(s) - gene , hydrogenase , structural gene , mutant , escherichia coli , biology , genetics , mutagenesis , site directed mutagenesis , biochemistry , bacteria
In Azotobacter chroococcum the hydrogenase structural genes ( hupSL ) cover about 2.8 kb of a 15‐kb region associated with hydrogen‐uptake (Hup) activity. Two other genes in this region, hupD and hupE , were located 8.9 kb downstream of hupL and were shown to be essential for hydrogenase activity by insertion mutagenesis. A fragment of DNA beginning 3.4 kb dowstream of hupL was able to complement the hupE mutant, supporting earlier evidence for a promoter downstream of hupSL . Hybridization experiments showed that hupD and hupE share some similarity with a region of Alcaligenes eutrophus DNA which is apparently involved in the formation of catalytically active hydrogenase. The hupD gene encodes a 379‐amino acid, 41.4‐kDa polypeptide while hupE codes for a 341‐amino acid, 36.1‐kDa product. The predicted amino acid sequences of the hupD and hupE genes are homologous to the Escherichia coli hypD and hypE gene products, respectively. A polar mutation in hupD had no effect on β‐galactosidase activity in a strain also carrying a hupL‐lacZ fusion, indicating that hupD and hupE are probably not involved in regulating hydrogenase structural gene expression.