The amino acid transport systems of the autotrophically grown green alga Chlorella

Cho, Bong‐Heuy; Komor, Ewald

doi:10.1016/0005-2736(85)90042-2

Cited by 22 publications

(11 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Chlorella sp. (a green alga), mutants defective in two distinct amino acid transports have been isolated (16), but there is kinetic evidence in favor of several other amino acid permeases in that organism (5,16).…”

Section: Resultsmentioning

confidence: 99%

Genetic analysis of amino acid transport in the facultatively heterotrophic cyanobacterium Synechocystis sp. strain 6803

1987

View full text Add to dashboard Cite

The existence of active transport systems (permeases) operating on amino acids in the photoautotrophic cyanobacterium Synechocystis sp. strain 6803 was demonstrated by following the initial rates of uptake with 14C-labeled amino acids, measuring the intracellular pools of amino acids, and isolating mutants resistant to toxic amino acids. One class of mutants (Pfa1) corresponds to a regulatory defect in the biosynthesis of the aromatic amino acids, but two other classes (Can1 and Aza1) are defective in amino acid transport. The Can1 mutants are defective in the active transport of three basic amino acids (arginine, histidine, and lysine) and in one of two transport systems operating on glutamine. The Aza1 mutants are not affected in the transport of the basic amino acids but have lost the capacity to transport all other amino acids except glutamate. The latter amino acid is probably transported by a third permease which could be identical to the Can1-independent transport operating on glutamine. Thus, genetic evidence suggests that strain 6803 has only a small number of amino acid transport systems with fairly broad specificity and that, with the exception of glutamine, each amino acid is accumulated by only one major transport system. Compared with heterotrophic bacteria such as Escherichia coli, these permeases are rather inefficient in terms of affinity (apparent Km ranging from 6 to 60 microM) and of Vmax.

show abstract

Section: Resultsmentioning

confidence: 99%

Genetic analysis of amino acid transport in the facultatively heterotrophic cyanobacterium Synechocystis sp. strain 6803

1987

View full text Add to dashboard Cite

show abstract

“…The low value for K( indicating high affinity for substrate) was similar to those of 7-10/fM (Van Sumere & Dedonder, 1971) and 28/tM (Cho & Komor, 1985) for phenylalanine uptake in Chlorella vulgaris and 5 fiM for phenylalanine uptake by Chlorella fusca (Pedersen & Knutsen, 1974). Uptake of phenylalanine by the cyanobacterium Microcystis PCC 7280 also showed a low K^, 20-2 (lU (Xu & McAuley, unpublished results).…”

Section: Uptake Of Phenylalaninementioning

confidence: 52%

“…Decreased number and non-specificity of amino-acid transport systems may be a consequence of integration of higher plant cells into tissue systems in which the extracellular environment is homeostatically maintained. Thus, the unicellular green alga Chlorella, subject to environmental fiuctuations in availability of amino acids, not only possesses uptake systems of broad specificity, but also at least three that take up only a single amino acid, methionine, threonine and glutamine respectively (Sauer, Komor & Tanner, 1983 ;Cho & Komor, 1985).…”

Section: Introductionmentioning

confidence: 99%

Uptake of amino acids by the cyanobacterium Anabaena ATCC 27893

McAuley

1990

New Phytologist

View full text Add to dashboard Cite

SUMMARYActive uptake of phenylalanine has been characterized in a species of cyanobacterium, Anabaena sp. ATCC 27893. Phenylalanine was apparently taken up by only one transport system over the concentration range 2-50/^M. Inhibition of phenylalanine uptake by glutamate and a range of neutral amino acids suggested that these were internalized by the same system. At least one other system appeared to be present, transporting the basic amino acids arginine and lysine. The K^ and F^^^ of phenylalanine uptake were comparable to those of phenylalanine uptake in eukaryotic unicellular freshwater algae. Uptake was energy dependent and internalized phenylalanine was rapidly incorporated into trichloracetic acid-insoluble material.

show abstract

“…has shown to assimilate amino-N by the use of cell-surface amino oxidase activity [26]. Chlorella was reported to possess both general and specific amino acid transport system [27]. The uptake of amino acid in M. aeruginosa may be by the special transport system, the amino oxidase or other unknown process.…”

Section: Discussionmentioning

confidence: 99%