Dimeric chlorite dismutase from the nitrogen-fixing cyanobacterium Cyanothece sp. PCC7425.

ABSTRACT: It is demonstrated that cyanobacteria (both azotrophic and non-azotrophic) contain heme b oxidoreductases that can convert chlorite to chloride and molecular oxygen (incorrectly denominated chlorite 'dismutase', Cld). Beside the water-splitting manganese complex of photosystem II, this metalloenzyme is the second known enzyme that catalyses the formation of a covalent oxygen-oxygen bond. All cyanobacterial Clds have a truncated N-terminus and are dimeric (i.e. clade 2) proteins. As model protein, Cld from Cyanothece sp. PCC7425 (CCld) was recombinantly produced in Escherichia coli and shown to efficiently degrade chlorite with an activity optimum at pH 5.0 [kcat 1144 ± 23.8 s(-1), KM 162 ± 10.0 μM, catalytic efficiency (7.1 ± 0.6) × 10(6) M(-1) s(-1)]. The resting ferric high-spin axially

SUBMITTER: Schaffner I 

PROVIDER: S-EPMC4973843 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature