Premium
A respiratory nitrate reductase active exclusively in resting spores of the obligate aerobe S treptomyces coelicolor A 3(2)
Author(s) -
Fischer Marco,
Falke Dörte,
Sawers R. Gary
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12344
Subject(s) - spore , streptomyces coelicolor , biology , nitrate reductase , hypha , nitrate , biochemistry , microbiology and biotechnology , obligate , enzyme , botany , mutant , ecology , gene
Summary The G ram‐positive aerobe S treptomyces coelicolor undergoes a complex life cycle including growth as vegetative hyphae and the production of aerial hyphae and spores. Little is known about how spores retain viability in the presence of oxygen; however, nothing is known about this process during anaerobiosis. Here, we demonstrate that one of the three respiratory nitrate reductases, Nar ‐1, synthesized by S . coelicolor is functional exclusively in spores. A tight coupling between nitrite production and the activity of the cytoplasmically oriented Nar ‐1 enzyme was demonstrated. No exogenous electron donor was required to drive nitrate reduction, which indicates that spore storage compounds are used as electron donors. Oxygen reversibly inhibited nitrate reduction by spores but not by spore extracts, suggesting that nitrate transport might be the target of oxygen inhibition. Nar ‐1 activity required no de novo protein synthesis indicating that Nar ‐1 is synthesized during sporulation and remains in a latently active state throughout the lifetime of the spore. Remarkably, the rates of oxygen and of nitrate reduction by wetted spores were comparable. Together, these findings suggest that S . coelicolor spores have the potential to maintain a membrane potential using nitrate as an alternative electron acceptor.