Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TRICHOMONAS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed2005

Spliceosomal introns in the deep-branching eukaryote Trichomonas vaginalis.

Eukaryotes have evolved elaborate splicing mechanisms to remove introns that would otherwise destroy the protein-coding capacity of genes. Nuclear premRNA splicing requires sequence motifs in the intron and is mediated by a ribonucleoprotein complex, the spliceosome. Here we demonstrate the presence of a splicing apparatus in the protist Trichomonas vaginalis and show that RNA motifs found in yeast and metazoan introns are required for splicing. We also describe the first introns in this deep-branching lineage. The positions of these introns are often conserved in orthologous genes, indicating they were present in a common ancestor of trichomonads, yeast, and metazoa. All examined T. vaginalis introns have a highly conserved 12-nt 3' splice-site motif that encompasses the branch point and is necessary for splicing. This motif is also found in the only described intron in a gene from another deep-branching eukaryote, Giardia intestinalis. These studies demonstrate the conservation of intron splicing signals across large evolutionary distances, reveal unexpected motif conservation in deep-branching lineages that suggest a simplified mechanism of splicing in primitive unicellular eukaryotes, and support the presence of introns in the earliest eukaryote.

Animals↗
PubMed2026

Impact of pH and Mycoplasma hominis endosymbiosis on Trichomonas vaginalis pathogenesis.

The parasite Trichomonas vaginalis colonizes the human vaginal tract and adheres to and lyses epithelial cells causing an inflammatory infection. The vaginal tract is typically acidic, ranging from pH 3.8 to 5.1; however, pathogenesis studies have previously been conducted on parasites grown at pH 5.9 to 6.2. Here we compared the adherence and cytotoxicity of T. vaginalis grown at pH 5.1 and pH 5.9, identifying changes in the surface proteome that contribute to increased pathogenesis of the parasite at pH 5.1. We show that growth of the parasite at pH 5.1 significantly enhances adherence to and lysis of host cells and that this is strongly amplified by the presence of a common bacterial endosymbiont, Mycoplasma hominis. Quantitative proteomics revealed the upregulation of putative surface proteins, three of which were found to be involved in increased parasite adherence and host cell killing. Mechanistic assays demonstrated that a Ricin B-like protein mediates parasite adherence dependent on host glycosaminoglycans via its carbohydrate-recognition domain, while an EF-hand-like protein is shown to promote Ca2+dependent adherence. Ricin B overexpression was found to reprogram host metabolism, activating ERK1/2 and HIF-1α and driving a Warburg-like glycolytic shift with greatly increased lactate release, which may create a nutrient-rich niche that supports parasite persistence and host cell cytotoxicity. These studies demonstrate a coordinated upregulation of multiple adhesins rather than a single factor at pH 5.1 in the presence of M. hominis and explore the mechanisms underlying the interaction of parasite surface proteins with the host cell.

Trichomonas vaginalis↗
PubMed1986

The double-stranded RNA in Trichomonas vaginalis may originate from virus-like particles.

A linear 5.5-kilobase double-stranded RNA, identified in many strains and isolates of the parasitic protozoan Trichomonas vaginalis in a previous study, is found largely intact in ribonuclease-treated homogenates of the parasite. It can be pelleted with membranes from the homogenate at 12,500 X g and further purified in CsCl buoyant density-gradient centrifugations. The purified sample contains the double-stranded RNA as well as one major protein with an estimated molecular mass of 85 kDa in NaDodSO4/PAGE. Electron microscopic examinations indicated the presence of icosahedral virus-like particles of 33-nm diameter in the purified preparation. The exact location of the virus in T. vaginalis is not clear, except that it is not found in the nuclear fraction and is probably membrane-bound. No free virus can be recovered from the culture medium of T. vaginalis, and no successful infection of virus-free T. vaginalis strains by purified virus has yet been accomplished. There is no viral genomic sequence identifiable in host DNA. So far as we know, it is the first time a double-stranded RNA virus has been identified in a protozoan.

Genes, Viral↗
PubMed1990

Molecular analysis of the hydrogenosomal ferredoxin of the anaerobic protist Trichomonas vaginalis.

We have determined the primary structure of the [2Fe-2S]ferredoxin of the anaerobic protist Trichomonas vaginalis. This protein, situated in the hydrogenosome, is composed of 93 amino acids. A comparison of T. vaginalis ferredoxin with greater than 80 other ferredoxins shows the closest similarity to [2Fe-2S]putidaredoxin of the aerobic bacterium Pseudomonas putida and a lesser one to mitochondrial [2Fe-2S]ferredoxins of vertebrates. This similarity is reflected in the overall primary structure and in the spacing of cysteine residues coordinating the iron-sulfur center. The primary structure, but not the environment of the iron-sulfur center, also shows similarity with [2Fe-2S]ferredoxins of photosynthetic organisms and halobacteria. We have cloned and analyzed the T. vaginalis ferredoxin gene. The gene is present in a single copy and devoid of introns. It gives rise to a transcript with unusually short 5' and 3' untranslated regions of 16 and 18 nucleotides, respectively. DNA sequence analysis of the gene predicts an additional 8 amino acids at the amino terminus which are absent from the purified protein. This amino-terminal region of the protein is characterized by properties typical of mitochondrial presequences.

Amino Acid Sequence↗
PubMed1992

Reduced transcription of the ferredoxin gene in metronidazole-resistant Trichomonas vaginalis.

Metronidazole [1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole] is used to treat infections caused by Trichomonas vaginalis, a sexually transmitted human parasite. This drug is administered in an inactive form and is reduced to its cytotoxic form within the hydrogenosome, an unusual organelle found in trichomonads. Metronidazole reduction occurs via ferredoxin-mediated electron transport. We have investigated the role of ferredoxin in metronidazole resistance. Immunoblot analysis of drug-resistant and -sensitive T. vaginalis strains shows that intracellular levels of ferredoxin are invariably reduced in the resistant strains relative to a sensitive strain. Similarly, Northern blot analysis shows that ferredoxin mRNA levels are reduced 50-65% in resistant strains. Using nuclear run-on assays, we show that ferredoxin gene transcription is reduced 40-65% in resistant strains. Sequence comparison of the region 5' of the ferredoxin gene among drug-sensitive and -resistant strains reveals two point mutations, at -178 and -239 nucleotides relative to the start of transcription, in a resistant strain. Interestingly, a protein of approximately 23 kDa binds to a 28-base-pair region that encompasses the mutation at -239 nucleotides. The binding affinity of this protein appears to be reduced in the mutant. These data strongly correlate drug resistance with altered regulation of ferredoxin gene transcription. A reduction in gene transcription results in decreased intracellular levels of ferredoxin. This, in turn, may play a role in metronidazole resistance by decreasing the ability of the cell to activate the drug.

Animals↗
PubMed1996

Presence of a mitochondrial-type 70-kDa heat shock protein in Trichomonas vaginalis suggests a very early mitochondrial endosymbiosis in eukaryotes.

Molecular phylogenetic analyses, based mainly on ribosomal RNA, show that three amitochondriate protist lineages, diplomonads, microsporidia, and trichomonads, emerge consistently at the base of the eukaryotic tree before groups having mitochondria. This suggests that these groups could have diverged before the mitochondrial endosymbiosis. Nevertheless, since all these organisms live in anaerobic environments, the absence of mitochondria might be due to secondary loss, as demonstrated for the later emerging eukaryote Entamoeba histolytica. We have now isolated from Trichomonas vaginalis a gene encoding a chaperone protein (HSP70) that in other lineages is addressed to the mitochondrial compartment. The phylogenetic reconstruction unambiguously located this HSP70 within a large set of mitochondrial sequences, itself a sister-group of alpha-purple bacteria. In addition, the T. vaginalis protein exhibits the GDAWV sequence signature, so far exclusively found in mitochondrial HSP70 and in proteobacterial dnaK. Thus mitochondrial endosymbiosis could have occurred earlier than previously assumed. The trichomonad double membrane-bounded organelles, the hydrogenosomes, could have evolved from mitochondria.

Amino Acid Sequence↗
PubMed1996

A possible mitochondrial gene in the early-branching amitochondriate protist Trichomonas vaginalis.

Trichomonads are anaerobic flagellated protists that, based on analyses of ribosomal RNA sequences, represent one of the earliest branching lineages among the eukaryotes. The absence of mitochondria in these organisms coupled with their deep phylogenetic position has prompted several authors to suggest that trichomonads, along with other deeply-branching amitochondriate protist groups, diverged from the main eukaryotic lineage prior to the endosymbiotic origin of mitochondria. In this report we describe the presence of a gene in Trichomonas vaginalis specifically related to mitochondrial chaperonin 60 (cpn60). A recent study indicates that a protein immunologically related to cpn60 is located in trichomonad hydrogenosomes. Together, these data provide evidence that ancestors of trichomonads perhaps harbored the endosymbiotic progenitors of mitochondria, but that these evolved into hydrogenosomes early in trichomonad evolution.

Animals↗
PubMed1997

Transient and selectable transformation of the parasitic protist Trichomonas vaginalis.

We have developed methods to transiently and selectably transform the human-infective protist Trichomonas vaginalis. This parasite, a common cause of vaginitis worldwide, is one of the earlier branching eukaryotes studied to date. We have introduced three heterologous genes into T. vaginalis by electroporation and have used the 5' and 3' untranslated regions of the endogenous gene alpha-succinyl CoA synthetase B (alpha-SCSB) to drive transcription of these genes. Transient expression of two reporter proteins, chloramphenicol acetyltransferase (CAT) or luciferase, was detected when electroporating in the presence of 50 microg closed-circular construct. Optimal levels of expression were observed using approximately 2.5 x 10(8) T. vaginalis cells and 350 volts, 960 microFd for electroporation; however, other conditions also led to significant reporter gene expression. A time course following the expression of CAT in T. vaginalis transient transformants revealed the highest level of expression 8-21 hr postelectroporation and showed that CAT activity is undetectable using TLC by 99 hr postelectroporation. The system we established to obtain selectable transformants uses the neomycin phosphotransferase (neo) gene as the selectable marker. Cells electroporated with 20 microg of the NEO construct were plated in the presence of 50 microg/ml paromomycin and incubated in an anaerobic chamber. The paromomycin-resistant colonies that formed within 3-5 days were cultivated in the presence of drug and DNA was isolated for analyses. The NEO construct was shown to be maintained episomally, as a closed-circle, at between 10-30 copies per cell. The ability to transiently and selectably transform T. vaginalis should greatly enhance research on this important human parasite.

Animals↗
PubMed1998

Secondary absence of mitochondria in Giardia lamblia and Trichomonas vaginalis revealed by valyl-tRNA synthetase phylogeny.

Nuclear-coded valyl-tRNA synthetase (ValRS) of eukaryotes is regarded of mitochondrial origin. Complete ValRS sequences obtained by us from two amitochondriate protists, the diplomonad, Giardia lamblia and the parabasalid, Trichomonas vaginalis were of the eukaryotic type, strongly suggesting an identical history of ValRS in all eukaryotes studied so far. The findings indicate that diplomonads are secondarily amitochondriate and give further evidence for such conclusion reached recently concerning parabasalids. Together with similar findings on other amitochondriate groups (microsporidia and entamoebids), this work provides critical support for the emerging notion that no representatives of the premitochondrial stage of eukaryotic phylogenesis exist among the species living today.

Amino Acid Sequence↗
PubMed1999

Convergent evolution of Trichomonas vaginalis lactate dehydrogenase from malate dehydrogenase.

Lactate dehydrogenase (LDH) is present in the amitochondriate parasitic protist Trichomonas vaginalis and some but not all other trichomonad species. The derived amino acid sequence of T. vaginalis LDH (TvLDH) was found to be more closely related to the cytosolic malate dehydrogenase (MDH) of the same species than to any other LDH. A key difference between the two T. vaginalis sequences was that Arg91 of MDH, known to be important in coordinating the C-4 carboxyl of oxalacetate/malate, was replaced by Leu91 in LDH. The change Leu91Arg by site-directed mutagenesis converted TvLDH into an MDH. The reverse single amino acid change Arg91Leu in TvMDH, however, gave a product with no measurable LDH activity. Phylogenetic reconstructions indicate that TvLDH arose from an MDH relatively recently.

Amino Acid Sequence↗
PubMed1996

Expression and spectroscopic characterization of the hydrogenosomal [2Fe-2S] ferredoxin from the protozoan Trichomonas vaginalis.

The heterologous expression and spectroscopic characterization of the [2Fe-2S] ferredoxin from the sexually transmitted human parasite Trichomonas vaginalis is described. Using oligonucleotide primers based on the deduced DNA sequence, the gene encoding the ferredoxin was amplified by polymerase chain reaction and cloned into a T7 RNA polymerase expression vector. Expression of the gene in Escherichia coli host HMS174(DE3) resulted in the high level production of the protein with the correctly assembled iron-sulfur cluster. The absorption, circular dichroism, resonance Raman, and EPR spectra of the recombinant protein revealed many differences from those of other [2Fe-2S] ferredoxins. The redox potential of the protein (-347 mV versus normal hydrogen electrode) was also determined. Whereas the amino acid sequence of T. vaginalis ferredoxin showed greatest homology to the [2Fe-2S] ferredoxins found in bacteria and vertebrate mitochondria which function in cytochrome P450 oxidation pathways, the spectroscopic properties showed substantial dissimilarity. Differences in the biophysical properties and function of T. vaginalis ferredoxin are proposed to result from the characteristic amino acid sequence of the parasite protein near the cysteine residues that ligate the valence-localized Fe(III) site of the reduced cluster.

Adrenodoxin↗
PubMed1998

The primitive protozoon Trichomonas vaginalis contains two methionine gamma-lyase genes that encode members of the gamma-family of pyridoxal 5'-phosphate-dependent enzymes.

Methionine gamma-lyase, the enzyme that catalyzes the breakdown of methionine by an alpha,gamma-elimination reaction and is a member of the gamma-family of pyridoxal 5'-phosphate-dependent enzymes, is present in high activity in the primitive protozoan parasite Trichomonas vaginalis but is absent from mammals. Two genes, mgl1 and mgl2, encoding methionine gamma-lyase, have now been isolated from T. vaginalis. They are both single copy, encode predicted proteins (MGL1 and MGL2) of 43 kDa, have 69% sequence identity with each other, and show a high degree of sequence identity to methionine gamma-lyase from Pseudomonas putida (44%) and other related pyridoxal 5'-phosphate-dependent enzymes such as human cystathionine gamma-lyase (42%) and Escherichia coli cystathionine beta-lyase (30%). mgl1 and mgl2 have been expressed in E. coli as a fusion with a six-histidine tag and the recombinant proteins (rMGL1 and rMGL2) purified by metal-chelate affinity chromatography. rMGL1 and rMGL2 were found to have high activity toward methionine (10.4 and 0.67 mumol/min/mg of protein, respectively), homocysteine (370 and 128 mumol/min/mg of protein), cysteine (6.02 and 1.06 mumol/min/mg of protein), and O-acetylserine (3.74 and 1.51 mumol/min/mg of protein), but to be inactive toward cystathionine. Site-directed mutagenesis of an active site cysteine (C113G for MGL1 and C116G for MGL2) reduced the activity of the recombinant enzymes toward both methionine and homocysteine by approximately 80% (rMGL1) and 90% (rMGL2). In contrast, the activity of mutated rMGL2 toward cysteine and O-acetylserine was increased (to 214 and 142%, respectively), whereas that of mutated rMGL1 was reduced to 39 and 49%, respectively. These findings demonstrate the importance of this cysteine residue in the alpha,beta-elimination and alpha, gamma-elimination reactions catalyzed by trichomonad methionine gamma-lyase.

Amino Acid Sequence↗
PubMed2001

Characterization of an iron-responsive promoter in the protozoan pathogen Trichomonas vaginalis.

Iron has been shown to regulate transcription in the protozoan pathogen Trichomonas vaginalis. In this study, a DNA transfection system was developed to monitor ap65-1 promoter activity in response to changing iron supply. In conjunction with electrophoretic mobility shift assay, iron-induced transcription of the ap65-1 gene was shown to be regulated by multiple closely spaced DNA elements spanning an iron-responsive region (-110/-54), including an iron-responsive DNA element ((-98)AGATAACGA(-90)), which overlaps with a 3'-MYB-like protein binding sequence ((-95)TAACGATAT(-87)), and three nearby T-rich sequences ((-110)ATTTTT(-105), (-78)ATTATT(-73), and (-59)ATTTTT(-54)). 5'- and 3'-flanking sequences of the iron-responsive region were shown to regulate basal transcription. A distal DNA regulatory region was shown to enhance both basal and iron-induced transcription. These findings delineate the DNA regulatory elements and nuclear proteins involving in iron-induced transcription of the ap65-1 gene, which provide useful tools for the future study of transcriptional regulation in T. vaginalis.

Animals↗
PubMed2003

Trichomonas vaginalis Hmp35, a putative pore-forming hydrogenosomal membrane protein, can form a complex in yeast mitochondria.

An abundant integral membrane protein, Hmp35, has been isolated from hydrogenosomes of Trichomonas vaginalis. This protein has no known homologue and exists as a stable 300-kDa complex, termed HMP35, in membranes of the hydrogenosome. By using blue native gel electrophoresis, we found the HMP35 complex to be stable in 2 m NaCl and up to 5 m urea. The endogenous Hmp35 protein was largely protease-resistant. The protein has a predominantly beta-sheet structure and predicted transmembrane domains that may form a pore. Interestingly, the protein has a high number of cysteine residues, some of which are arranged in motifs that resemble the RING finger, suggesting that they could be coordinating zinc or another divalent cation. Our data show that Hmp35 forms one intramolecular but no intermolecular disulfide bonds. We have isolated the HMP35 complex by expressing a His-tagged Hmp35 protein in vivo followed by purification with nickel-agarose beads. The purified 300-kDa complex consists of mostly Hmp35 with lesser amounts of 12-, 25-27-, and 32-kDa proteins. The stoichiometry of proteins in the complex indicates that Hmp35 exists as an oligomer. Hmp35 can be targeted heterologously into yeast mitochondria, despite the lack of homology with any yeast protein, demonstrating the compatibility of mitochondrial and hydrogenosomal protein translocation machineries.

Amino Acid Sequence↗
PubMed2005

Identification of Trichomonas vaginalis cysteine proteases that induce apoptosis in human vaginal epithelial cells.

A secreted cysteine protease (CP) fraction from Trichomonas vaginalis is shown here to induce apoptosis in human vaginal epithelial cells (HVEC) and is analyzed by mass spectrometry. The trichomonad parasite T. vaginalis causes one of the most common non-viral sexually transmitted infection in humans, trichomoniasis. The parasite as well as a secreted cysteine protease (CP) fraction, isolated by affinity chromatography followed by Bio-Gel P-60 column chromatography, are shown to induce HVEC apoptosis, as demonstrated by the Cell Death Detection ELISA(PLUS) assay and annexin V-fluorescein isothiocyanate flow cytometry analyses. Initiation of apoptosis is correlated with protease activity because the specific CP inhibitor E-64 inhibits both activities. SDS-PAGE analysis of the CP fraction reveals triplet bands around 30 kDa, and matrix-assisted laser desorption ionization time-of-flight MS indicates two closely associated peaks of molecular mass 23.6 and 23.8 kDa. Mass spectral peptide sequencing of the proteolytically digested CPs results in matches to previously reported cDNA clones, CP2, CP3, and CP4 (Mallinson, D. J., Lockwood, B. C., Coombs, G. H., and North, M. J. (1994) Microbiology 140, 2725-2735), as well as another sequence with high homology to CP4 (www.tigr.org). These last two species are the most abundant components of the CP fraction. The present results, suggesting that CP-induced programmed cell death may be involved in the pathogenesis of T. vaginalis infection in vivo, may have important implications for therapeutic intervention.

Amino Acid Sequence↗
PubMed2005

Identification of a subversive substrate of Trichomonas vaginalis purine nucleoside phosphorylase and the crystal structure of the enzyme-substrate complex.

Trichomonas vaginalis is an anaerobic protozoan parasite that causes trichomoniasis, a common sexually transmitted disease with worldwide impact. One of the pivotal enzymes in its purine salvage pathway, purine nucleoside phosphorylase (PNP), shows physical properties and substrate specificities similar to those of the high molecular mass bacterial PNPs but differing from those of human PNP. While carrying out studies to identify inhibitors of T. vaginalis PNP (TvPNP), we discovered that the nontoxic nucleoside analogue 2-fluoro-2'-deoxyadenosine (F-dAdo) is a "subversive substrate." Phosphorolysis by TvPNP of F-dAdo, which is not a substrate for human PNP, releases highly cytotoxic 2-fluoroadenine (F-Ade). In vitro studies showed that both F-dAdo and F-Ade exert strong inhibition of T. vaginalis growth with estimated IC(50) values of 106 and 84 nm, respectively, suggesting that F-dAdo might be useful as a potential chemotherapeutic agent against T. vaginalis. To understand the basis of TvPNP specificity, the structures of TvPNP complexed with F-dAdo, 2-fluoroadenosine, formycin A, adenosine, inosine, or 2'-deoxyinosine were determined by x-ray crystallography with resolutions ranging from 2.4 to 2.9 A. These studies showed that the quaternary structure, monomer fold, and active site are similar to those of Escherichia coli PNP. The principal active site difference is at Thr-156, which is alanine in E. coli PNP. In the complex of TvPNP with F-dAdo, Thr-156 causes the purine base to tilt and shift by 0.5 A as compared with the binding scheme of F-dAdo in E. coli PNP. The structures of the TvPNP complexes suggest opportunities for further improved subversive substrates beyond F-dAdo.

Adenine↗
PubMed2006

Cysteine biosynthesis in Trichomonas vaginalis involves cysteine synthase utilizing O-phosphoserine.

Trichomonas vaginalis is an early divergent eukaryote with many unusual biochemical features. It is an anaerobic protozoan parasite of humans that is thought to rely heavily on cysteine as a major redox buffer, because it lacks glutathione. We report here that for synthesis of cysteine from sulfide, T. vaginalis relies upon cysteine synthase. The enzyme (TvCS1) can use either O-acetylserine or O-phosphoserine as substrates. The K(m) values of the enzyme for sulfide are very low (0.02 mm), suggesting that the enzyme may be a means of ensuring that sulfide in the parasite is maintained at a low level. T. vaginalis appears to lack serine acetyltransferase, the source of O-acetylserine in many cells, but has a functional 3-phosphoglycerate dehydrogenase and an O-phosphoserine aminotransferase that together result in the production of O-phosphoserine, suggesting that this is the physiological substrate. TvCS1 can also use thiosulfate as substrate. Overall, TvCS1 has substrate specificities similar to those reported for cysteine synthases of Aeropyrum pernix and Escherichia coli, and this is reflected by sequence similarities around the active site. We suggest that these enzymes are classified together as type B cysteine synthases, and we hypothesize that the use of O-phosphoserine is a common characteristic of these cysteine synthases. The level of cysteine synthase in T. vaginalis is regulated according to need, such that parasites growing in an environment rich in cysteine have low activity, whereas exposure to propargylglycine results in elevated cysteine synthase activity. Humans lack cysteine synthase; therefore, this parasite enzyme could be an exploitable drug target.

Amino Acid Sequence↗
PubMed2007

Activation of multifarious transcription of an adhesion protein ap65-1 gene by a novel Myb2 protein in the protozoan parasite Trichomonas vaginalis.

Multifarious transcription of the adhesion protein ap65-1 gene in the human pathogen, Trichomonas vaginalis, is critically regulated by the coordination of two similar but opposite oriented DNA regulatory regions, MRE-1/MRE-2r and MRE-2f, both of which are binding sites for multiple Myb-like proteins. In the present study, MRE-1/MRE-2r was demonstrated to be composed of multiple overlapping promoter elements, among which the entire region is required for growth-related ap65-1 transcription, and the 5'-MRE-1 antagonizes the suppressive activity of the 3'-MRE-2r in iron-inducible transcription. The recombinant Myb2 protein derived from a previously identified myb2 gene was demonstrated to recognize distinct sequence contexts in MRE-2r and MRE-2f, whereas Myb2 in the nuclear lysate preferentially binds to MRE-2f to MRE-2r. Iron repletion resulted in persistent repression of the myb2 gene, and temporal activation/deactivation of Myb2 promoter entry, which was also activated by prolonged iron depletion. The hemagglutinintagged Myb2 when overexpressed during iron-depleted conditions facilitated basal and growth-related ap65-1 transcription to a level that was achieved in iron-replete cells, whereas ironinducible ap65-1 transcription was abolished with knockdown of Myb2. These findings demonstrated that Myb2 is involved in activation of growth-related and iron-inducible transcription of the ap65-1 gene, possibly through differential promoter selection in competition with other Myb proteins.

Animals↗