Open AccessCharacterization of a c ‐type heme‐containing PAS sensor domain from Geobacter sulfurreducens representing a novel family of periplasmic sensors in Geobacteraceae and other bacteria
Author(s) -
Londer Yuri Y.,
Dementieva Irina S.,
D'Ausilio Cori A.,
Pokkuluri P. Raj,
Schiffer Marianne
Publication year - 2006
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.1574-6968.2006.00220.x
Subject(s) - periplasmic space , geobacter sulfurreducens , pas domain , heme , biology , bacterial outer membrane , chemistry , biochemistry , escherichia coli , dimer , bacteria , genetics , gene , enzyme , organic chemistry , biofilm , transcription factor
Geobacter sulfurreducens encodes one of the largest numbers of proteins annotated as parts of the two‐component signal transduction and/or chemotaxis pathways. Ten of these signal transducers have homologous periplasmic sensor domains that contain the sequence signature for c ‐type hemes. One such sensor domain encoded by gene GSU0303 was isolated and characterized. The protein was expressed in Escherichia coli and was isolated as two colored species (green and red). The green species is a monomer of the sensor domain with a five‐coordinated high‐spin heme and the red species is probably a noncovalent dimer of the sensor domain which might have an uncharacterized ligand bound to the dimer. The UV‐VIS spectrum of the green species indicates that it has a c ′‐type heme, but its structure is predicted to be homologous to CitA, a periplasmic PAS domain that does not contain heme. The GSU0303 sensor domain represents a previously unreported family of PAS‐type periplasmic sensor domains that contain c ‐type hemes; these proteins could be part of an important mechanism for sensing redox potential or small ligands in the periplasm. Homologs to the sensor domains we identified in G. sulfurreducens are observed in various bacteria although they occur in larger numbers in the Geobacteraceae .