Haem-based sensors: a still growing old superfamily.
The haem-based sensors are chimeric multi-domain proteins responsible for the cellular adaptive responses to environmental changes. The signal transduction is mediated by the sensing capability of the haem-binding domain, which transmits a usable signal to the cognate transmitter domain, responsible for providing the adequate answer. Four major families of haem-based sensors can be recognized, depending on the nature of the haem-binding domain: (i) the haem-binding PAS domain, (ii) the CO-sensitive carbon monoxide oxidation activator, (iii) the haem NO-binding domain, and (iv) the globin-coupled sensors. The functional classification of the haem-binding sensors is based on the activity of the transmitter domain and, traditionally, comprises: (i) sensors with aerotactic function; (ii) sensors with gene-regulating function; and (iii) sensors with unknown function. We have implemented this classification with newly identified proteins, that is, the Streptomyces avermitilis and Frankia sp. that present a C-terminal-truncated globin fused to an N-terminal cofactor-free monooxygenase, the structural-related class of non-haem globins in Bacillus subtilis, Moorella thermoacetica, and Bacillus anthracis, and a haemerythrin-coupled diguanylate cyclase in Vibrio cholerae. This review summarizes the structures, the functions, and the structure-function relationships known to date on this broad protein family. We also propose unresolved questions and new possible research approaches.
Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
Francesca
F
Germani
Luc
L
Moens
Sylvia
S
Dewilde
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial; D005914:Globins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D015398:Signal Transduction
D001426:Bacterial Proteins; D006418:Heme; D005914:Globins
Chimeric proteins; Gene regulating; Globin-coupled sensors; Haem-based sensors; Structure–function relationship