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Cloning of two genes encoding potassium transporters in Neurospora crassa and expression of the corresponding cDNAs in Saccharomyces cerevisiae
Author(s) -
Haro Rosario,
Sainz Loreto,
Rubio Francisco,
RodríguezNavarro Alonso
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01192.x
Subject(s) - neurospora crassa , biology , saccharomyces cerevisiae , schizosaccharomyces pombe , crassa , mutant , transporter , symporter , biochemistry , gene , permease , complementary dna , yeast , microbiology and biotechnology
Two Neurospora crassa genes, trk‐1 and hak‐1 , encode K + transporters that show sequence similarities to the TRK transporters described in Saccharomyces cerevisiae and Schizosaccharomyces pombe , and to the HAK transporters described in Schwanniomyces occidentalis and barley. The N. crassa TRK1 and HAK1 transporters expressed by the corresponding cDNAs in a trk1Δ trk2Δ mutant of S. cerevisiae exhibited a high affinity for Rb + and K + . Northern blot analysis and comparison of the kinetic characteristics of the two transporters in the trk1Δ trk2Δ mutant with the kinetic characteristics of K + uptake in N. crassa cells allowed TRK1 to be identified as the dominant K + transporter and HAK1 as a transporter that is only expressed when the cells are K + starved. The HAK1 transporter showed a high concentrative capacity and is identified as the K + –H + symporter described in N. crassa , whereas TRK1 might be a K + uniporter. Although the co‐existence of K + transporters of the TRK and HAK types in the same species had not been reported formerly, we discuss whether this co‐existence may be the normal situation in soil fungi.