Differential expression of citA gene encoding the mitochondrial citrate synthase of Aspergillus nidulans in response to developmental status and carbon sources.
As an extension of our previous studies on the mitochondrial citrate synthase of Aspergillus nidulans and cloning of its coding gene (citA), we analyzed differential expression of citA in response to the progress of development and change of carbon source. The cDNA consisted of 1,700 nucleotides and was predicted to encode a 474-amino acid protein. By comparing the cDNA sequence with the corresponding genomic sequence, we confirmed that citA gene contains 7 introns and that its transcription starts at position -26 (26-nucleotide upstream from the initiation codon). Four putative CreA binding motifs and three putative stress-response elements (STREs) were found within the 1.45-kb citA promoter region. The mode of citA expression was examined by both Northern blot and confocal microscopy using green fluorescent protein (sGFP) as a vital reporter. During vegetative growth and asexual development, the expression of citA was ubiquitous throughout the whole fungal body including mycelia and conidiophores. During sexual development, the expression of citA was quite strong in cleistothecial shells, but significantly weak in the content of cleistothecia including ascospores. Acetate showed a strong inductive effect on citA expression, which is subjected to carbon catabolite repression (CCR) caused by glucose. The recombinant fusion protein CitA(40)::sGFP (sGFP containing the 40-amino acid N-terminal segment of CitA) was localized into mitochondria, which supports that a mitochondrial targeting signal is included within the 40-amino acid N-terminal segment of CitA.
Min
In Sook
IS
Department of Microbiology & Molecular Biology, Chungnam National University, Daejeon, 305-764, Republic of Korea.
Bang
Ji Young
JY
Seo
Soon Won
SW
Lee
Cheong Ho
CH
Maeng
Pil Jae
PJ
D000085:Acetates / Q000378:metabolism; D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D001483:Base Sequence; D001665:Binding Sites; D002244:Carbon / Q000378:metabolism*; D002950:Citrate (si)-Synthase / Q000096:biosynthesis* / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007438:Introns; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000737:chemistry; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021382:Protein Sorting Signals; D012097:Repressor Proteins / Q000378:metabolism; D024363:Transcription Initiation Site
D000085:Acetates; D018076:DNA, Complementary; D004271:DNA, Fungal; D005656:Fungal Proteins; D021382:Protein Sorting Signals; D012097:Repressor Proteins; C071237:CreA protein, Aspergillus nidulans; D049452:Green Fluorescent Proteins; D002244:Carbon; D002950:Citrate (si)-Synthase