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Nitrate transport in the cyanobacterium Anacystis nidulans
Author(s) -
Lara Catalina,
Rodríguez Rocío,
Guerrero Miguel G.
Publication year - 1993
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1993.tb05217.x
Subject(s) - nitrate , ammonium , chemistry , nitrogen assimilation , cyanobacteria , photosynthesis , sodium nitrate , membrane transport , biochemistry , nitrogen , environmental chemistry , inorganic chemistry , bacteria , membrane , biology , organic chemistry , genetics
A significant progress in the knowledge of different aspects of nitrate transport in the unicellular cyanobacterium Anacystis (Synechococcus ) has been achieved in the last few years. The main contributions of our group are summarized in this article and discussed in relation to other information available. Endergonic accumulation of nitrate into the cells, indicative of the operation of an active nitrate transport system, has been experimentally substantiated and methods established to evaluate and analyze the activity of the system. Nitrate transport activity is sensitive to regulation exerted by products of both ammonium and CO 2 assimilation, thus providing evidence that photosynthetic nitrate assimilation in cyanobacteria is primarily controlled at the level of substrate supply to the cell. The expression of nitrate transport was also shown to be under nitrogen control, being repressed when ammonium is used as the nitrogen source. A 47‐kDa polypeptide, which is a major plasma membrane component in nitrate‐grown cells but is virtually absent in ammonium‐grown cells, was identified as an essential component of the nitrate transporter. More recently, evidence of a strict Na'‐dependence of active nitrate transport has been obtained, Δμ(Na + ) appearing as the driving force of a sodium‐nitrate symport system. Kinetic studies indicate also that the nitrate transporter may transport nitrite into the cell.