Polyamine transport in Neurospora crassa

Davis, Rowland H.; Ristow, Janet L.

doi:10.1016/0003-9861(88)90054-9

Cited by 30 publications

(23 citation statements)

References 27 publications

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“…Ca 2ϩ is also known to affect polyamine transport into eukaryotes, although the effects are disparate. Ca 2ϩ stimulates polyamine uptake in human fibroblasts (48) and breast cancer cells (47), whereas the divalent cation inhibits polyamine transport into embryonic mesenchymal cells (49) and Neurospora crassa (50). Because the calcium ionophore A23687 inhibited putrescine uptake into TUB::HD309-LmPOT1 T. brucei, it is possible that putrescine transport via LmPOT1 is Ca 2ϩ -dependent.…”

Section: Discussionmentioning

confidence: 99%

Identification and Characterization of a Polyamine Permease from the Protozoan Parasite Leishmania major

Hasne

Ullman

2005

Journal of Biological Chemistry

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The proteins that mediate polyamine translocation into eukaryotic cells have not been identified at the molecular level. To define the polyamine transport pathways in eukaryotic cells we have cloned a gene, LmPOT1, that encodes a polyamine transporter from the protozoan pathogen, Leishmania major. Sequence analysis of LmPOT1 predicted an unusual 803-residue polytopic protein with 9 -12 transmembrane domains. Expression of LmPOT1 cRNA in Xenopus laevis oocytes revealed LmPOT1 to be a high affinity transporter for both putrescine and spermidine, whereas expression of LmPOT1 in Trypanosoma brucei stimulated putrescine uptake that was sensitive to inhibition by pentamidine and proton ionophores. Immunoblot analysis established that LmPOT1 was expressed predominantly in the insect vector form of L. major, and immunofluorescence demonstrated that LmPOT1 was localized predominantly to the parasite plasma membrane. To our knowledge this is the first molecular identification and characterization of a cell surface polyamine transporter in eukaryotic cells.

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Section: Discussionmentioning

confidence: 99%

Identification and Characterization of a Polyamine Permease from the Protozoan Parasite Leishmania major

Hasne

Ullman

2005

Journal of Biological Chemistry

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“…Wild type Neurospora cannot concentrate polyamines from Vogel's medium, because the saturable polyamine transport system is inhibited (1,2). Putrescine and spermidine equilibrate across the cell membrane by a diffusional mechanism (2).…”

Section: Altered Transport Characteristics Of the Puu-1 Mutantmentioning

confidence: 99%

“…The apparent Km's of the puu-1 strain were about 3 mM for both substrates under these conditions. After a wash and resuspension in Mops buffer (20 mM Na+), both strains displayed saturable polyamine uptake, with normal K,,,'s for putrescine (0.3-0.7 mM) and spermidine (0.25 mM) (1); the Km's were lower in buffer owing to lack of competitive inhibition by salts in the medium. The V,,, of uptake bypuu-1 strains in Mops buffer was 2.5 to 8 times greater than that of the wild type.…”

Section: Altered Transport Characteristics Of the Puu-1 Mutantmentioning

confidence: 99%

“…The organism has a polyamine transport system that takes up all three natural polyamines with moderate affinity (Km's: putrescine = 600 PM; spermidine = 240 PM; spermine = 70 PM) from a dilute buffer containing 20 mM Na+ (1). In the growth medium, however, this system is inhibited by monovalent cations and by Ca2+, and all transport of polyamines takes place by way of a nonsaturable, diffusional system that equilibrates polyamines across the cell membrane (1,2). The concentrative uptake system appears only in Ca'+-free buffers having low monovalent cation concentrations.…”

mentioning

confidence: 99%

“…The concentrative uptake system appears only in Ca'+-free buffers having low monovalent cation concentrations. We have in fact questioned whether the natural substrates of the system include the polyamines (1).…”

mentioning

confidence: 99%

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Calcium modulation of polyamine transport is lost in a putrescine-sensitive mutant of Neurospora crassa

Davis

Ristow

Howard

et al. 1991

Archives of Biochemistry and Biophysics

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Management of polyamine pools and the regulation of ornithine decarboxylase

Davis

1990

J of Cellular Biochemistry

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The management of polyamine synthesis and polyamine pools differs fundamentally from that of most other small molecular-weight endproducts. The polyamines are vital to growth and important cellular functions, but they are toxic in excess. I argue here that their multivalent cationic character, leading to binding to cell constituents, precludes fluent feedback inhibition of synthesis. This has led to the development of elaborate alternative regulatory mechanisms controlling ornithine decarboxylase, the key initial enzyme of the pathway. Poorly regulated polyamine synthesis and the toxicity of polyamines impose upon cells a need to control uptake and to dispose of excess polyamines. Recent data on polyamine transport suggest unorthodox mechanisms of accomplishing these functions.

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Polyamine transport in Neurospora crassa

Cited by 30 publications

References 27 publications

Identification and Characterization of a Polyamine Permease from the Protozoan Parasite Leishmania major

Identification and Characterization of a Polyamine Permease from the Protozoan Parasite Leishmania major

Calcium modulation of polyamine transport is lost in a putrescine-sensitive mutant of Neurospora crassa

Management of polyamine pools and the regulation of ornithine decarboxylase

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