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Sulphate transport in the cyanobacterium Synechococcus R‐2 ( Anacystis nidulans, S. leopoliensis ) PCC 7942
Author(s) -
RITCHIE R. J.
Publication year - 1996
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1996.tb00009.x
Subject(s) - dcmu , synechococcus , sodium , chemistry , nuclear chemistry , potassium , sodium azide , chloride , cyanobacteria , medicinal chemistry , stereochemistry , biochemistry , photosynthesis , bacteria , biology , photosystem ii , organic chemistry , genetics
Synechococcus R‐2 (PCC 1942) actively accumulates sulphate in the light and dark. Intracellular sulphate was 1.35 ± 0.23 mol m −3 (light) and 0.894 ± 0.152 mol m −3 (dark) under control conditions (BG‐11 media: pH o , 7.5; [SO 4 2− ] o , 0.304 mol m −3 ). The sulphate transporter is different from that found in higher plants: it appears to be an ATP‐driven pump transporting one SO 4 2− /ATP [ΔμSO 4 2− i,o =+ 27.7 ± 0.24 kJ mol −1 (light) and + 24 ± 0.34 kj mol −1 (dark)]. The rate of metabolism of SO 4 2− at pH o , 7.5 was 150 ± 28 pmol m −2 s −1 (n = 185) in the light but only 12.8 ± 3.6 pmol m −2 s −1 (n = 61) in the dark. Light‐driven sulphate uptake is partially inhibited by DCMU and chloramphenicol. Sulphate uptake is not linked to potassium, proton, sodium or chloride transport. The alga has a constitutive over‐capacity for sulphate uptake [light ( n = 105): K m = 0.3 ± 0.1 mmol m −3 , V max , = 1.8 ± 0.6 nmol m −2 s −1 ; dark ( n = 56): K m = 1.4 ± 0.4 mmol m −3 , V max = 41 ± 22 pmol m −2 s −1 ]. Sulphite (SO 3 2− ) was a competitive inhibitor of sulphate uptake. Selenate (SeO 4 2− ) was an uncompetitive inhibitor.