Aspartate 141 is the fourth ligand of the oxygen-sensing [4Fe-4S]2+ cluster of Bacillus subtilis transcriptional regulator Fnr.
The Bacillus subtilis redox regulator Fnr controls genes of the anaerobic metabolism in response to low oxygen tension. An unusual structure for the oxygen-sensing [4Fe-4S](2+) cluster was detected by a combination of genetic experiments with UV-visible and Mössbauer spectroscopy. Asp-141 was identified as the fourth iron-sulfur cluster ligand besides three Cys residues. Exchange of Asp-141 with Ala abolished functional in vivo complementation of an fnr knock-out strain by the mutagenized fnr gene and in vitro DNA binding of the recombinant regulator FnrD141A. In contrast, substitution of Asp-141 with Cys preserved [4Fe-4S](2+) structure and regulator function.
Institute of Microbiology, University Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany.
Ines
I
Gruner
Claudia
C
Frädrich
Lars H
LH
Böttger
Alfred X
AX
Trautwein
Dieter
D
Jahn
Elisabeth
E
Härtig
D019943:Amino Acid Substitution; D001224:Aspartic Acid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001412:Bacillus subtilis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D008024:Ligands; D014157:Transcription Factors; D001224:Aspartic Acid