Open AccessPurification and structural characterization of a flavoprotein induced by iron limitation in Methanobacterium thermoautotrophicum Marburg
Author(s) -
Alain Wasserfallen,
Kimberly Huber,
Thomas Leisinger
Publication year - 1995
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.177.9.2436-2441.1995
Subject(s) - flavoprotein , biology , homotetramer , flavin mononucleotide , biochemistry , rhodobacter , operon , methanobacterium , flavodoxin , peptide sequence , microbiology and biotechnology , protein subunit , sequence analysis , flavin adenine dinucleotide , flavin group , gene , cofactor , ferredoxin , enzyme , escherichia coli , mutant , archaea
Cells of Methanobacterium thermoautotrophicum (strain Marburg) grown under iron-limiting conditions were found to synthesize a soluble polypeptide as one of the major cell proteins. This polypeptide purified as a homotetramer (170 kDa [subunit molecular mass, 43 kDa]) had a UV-visible spectrum typical of flavoproteins and contained 0.7 mol of flavin mononucleotide per mol of monomer. Quantitative analysis by immunoblotting with polyclonal antibodies indicated that the flavoprotein, which amounts to about 0.6% of soluble cell protein under iron-sufficient conditions (> or = 50 microM Fe2+), was induced fivefold by iron limitation (< 12 microM Fe2+). The flavoprotein-encoding gene, fprA, was cloned and sequenced. Sequence analysis revealed a well-conserved archaebacterial consensus promoter upstream of fprA, a flavodoxin signature within fprA, and 28% amino acid identity with a putative flavin mononucleotide-containing protein of Rhodobacter capsulatus which is found within an operon involved in nitrogen fixation. A possible physiological function for the flavoprotein is discussed.