Occurrence of heme O in photoheterotrophically growing, semi‐anaerobic cyanobacterium Synechocystis sp. PCC6803

FEBS Letters

Fromwald, Susanne¹  Peschek, Günter A.¹  Wastyn, Marnik¹  Mayer, Bernhard¹ 

[1] Biophysical Chemistry Group, Institute of Physical Chemistry, University of Vienna, Währingerstrasse 42, A-1090 Vienna, Austria

关键词: Respiratory oxidase;    Respiratory electron transport;    Heme group;    Reversed phase HPLC;    Cyanobacteria;    Synechocystis sp. PCC 6803;    HPLC;    high performance liquid chromatography;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    HQNO;    2-n-heptyl-4hydroxy-quinoline N-oxide;    cyt;    cytochrome;   

DOI  :  10.1016/0014-5793(95)00821-P

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Extraction and identification of the non-covalently bound heme groups from crude membrane preparations of photoheterotrophically grown Synechocystis sp. PCC 6803 by reversed phase high performance liquid chromatography and optical spectrophotometry led to the detection of heme O in addition to hemes B and A which latter was to be expected from the known presence of aa₃-type cytochrome oxidase in cyanobacteria. In fully aerated cells (245 μM dissolved O₂ in the medium) besides heme B only heme A was found while in low-oxygen cells (<10 μM dissolved O₂) heme O was present at a concentration even higher than that of heme A. Given the possible role of heme O as a biosynthetic intermediate between heme B and heme A, together with generally much higher K _m values of 5–50 μM O₂ for oxygenase as compared to K _m values of 40–70 nM O₂ for typical cytochrome-c oxidase, our findings may permit the conclusion that the conversion of heme O to heme A is an obligately oxygen-requiring process catalyzed by some oxygenase directly introducing oxygen from O₂ into the 8-methyl group of heme O. At the same time thus the occurrence of heme O (cytochrome o) in cyanobacteria does of course not imply the existence of an ‘alternative oxidase’ since according to the well-known ‘promiscuity of heme groups’ both hemes O and A are likely to combine with one and the same apoprotein.

【 授权许可】

Unknown