Detection of an L-amino acid dehydrogenase activity in Synechocystis sp. PCC 6803.
The protein Slr0782 from Synechocystis sp. PCC 6803, which has similarity to L-amino acid oxidase from Synechococcus elongatus PCC 6301 and PCC 7942, has been characterized in part. Immunoblot blot analysis showed that Slr0782 is mainly thylakoid membrane-associated. Moreover, expression of slr0782 mRNA and Slr0782 protein were analyzed and an activity assay was developed. Utilizing toluene-permeabilized cells, an L-arginine-stimulated O(2) uptake became detectable in Synechocystis sp. PCC 6803. Besides oxidizing the basic L-amino acids L-arginine, L-lysine, L-ornithine, and L-histidine, a number of other L-amino acids were also substrates, while D-amino acids were not. The best substrate was L-cysteine, and the second best was L-arginine. The L-arginine-stimulated O(2) uptake was inhibited by cations. The inhibition by o-phenanthroline and salicylhydroxamic acid suggested the presence of a transition metal besides FAD in the enzyme. Moreover, it is shown that inhibitors of the respiratory electron transport chain, such as KCN and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, also inhibited the L-arginine-stimulated O(2) uptake, suggesting that Slr0782 functions as an L-arginine dehydrogenase, mediating electron transfer from L-arginine into the respiratory electron transport chain utilizing O(2) as electron acceptor via cytochrome oxidase. The results imply that Slr0782 is an additional substrate dehydrogenase being able to interact with the electron transport chain of the thylakoid membrane.
Schriek
Sarah
S
Lehrstuhl für Molekulare Zellphysiologie, Universität Bielefeld, Universitätsstr. 25, D-33615 Bielefeld, Germany.
Kahmann
Uwe
U
Staiger
Dorothee
D
Pistorius
Elfriede K
EK
Michel
Klaus-Peter
KP
D000594:Amino Acid Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019295:Computational Biology; D004579:Electron Transport; D004583:Electrons; D015964:Gene Expression Regulation, Bacterial; D015151:Immunoblotting; D007425:Intracellular Membranes / Q000201:enzymology; D008954:Models, Biological; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D046939:Synechocystis / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D020524:Thylakoids / Q000201:enzymology; D014867:Water
D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D014867:Water; D001120:Arginine; D000594:Amino Acid Oxidoreductases; D010100:Oxygen