Functional identification of high-affinity iron permeases from Fusarium graminearum.
The ScFTR1 gene encodes an iron permease in Saccharomyces cerevisiae. Its homologues, FgFtr1 and FgFtr2, were identified from filamentous pathogenic plant fungus, Fusarium graminearum. Homologies between the deduced amino acid sequences of ScFtr1p and FgFtr1 and FgFtr2 were 56 and 54%, respectively, and both had REXXE sequences, which form the conserved amino acid sequence of ScFtr1p. FgFtr1 expression increased under iron depletion, and although FgFtr2 mRNA was not detected in the wild-type strain, it was detected in the deltafgftr1 strain in the iron-depleted condition. When the FgFtr1 and FgFtr2 were deleted, the amount of growth was found not to be different from the wild-type in iron-depleted media. However, the mRNA of FgSid, a homologue of the SIDA of Aspergillus fumigatus, was dramatically increased in the deltafgftr1/deltafgftr2 strain and in an iron-depleted condition. FgFtr1 and FgFtr2 genes act as functional complements when they are introduced into the S. cerevisiae deltaScftr1 strain. The deltaScftr1 strain, which contains either the FgFtr1 or FgFtr2, grew well in iron-depleted media. Moreover, specific alteration of the REXXE consensus sequence of FgFtr1 and FgFtr2 did not allow for sustained growth of the deltaScftr1 strain on iron-depleted medium. The iron uptake activity was recovered when FgFtr1 and FgFtr2 genes were introduced into the deltaScftr1 strain. Though the Fet3p in S. cerevisiae was found on the intracellular vesicle in the deltaScftr1 strain, Fet3p was found on the plasma membrane when FgFtr1 or FgFtr2 was introduced into the deltaftr1 strain. An infection test was carried out with deletion strains; however, no change in the ability of these strains to cause disease was observed. These results suggest that FgFtr1 and FgFtr2 may function as iron permeases in the reductive iron uptake pathway and that they do not play major roles in the pathogenicity of F. graminearum.
Park
Yong-Sung
YS
School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea.
Choi
Il-Dong
ID
Kang
Chang-Min
CM
Ham
Mun-Sik
MS
Kim
Ji-Hyun
JH
Kim
Tae-Hyoung
TH
Yun
Sung-Hwan
SH
Lee
Yin-Won
YW
Chang
Hyo-Ihl
HI
Sung
Ha-Chin
HC
Yun
Cheol-Won
CW
D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D015139:Blotting, Southern; D017124:Conserved Sequence; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D005670:Fusarium / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D001467:Hordeum / Q000382:microbiology; D007501:Iron / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014774:Virulence
D004271:DNA, Fungal; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D007501:Iron