AtMBD4: A methylated DNA binding protein negatively regulates a subset of phosphate starvation genes

DNA methylation is an important epigenetic modification that governs transcriptional regulation. The methylation mark isread by a special class of proteins called methyl-CpG-binding domain proteins. The role of DNA methylation has beenfound in X-chromosome inactivation, genomic imprinting, transposon silencing, and self-incompatibility. Recently,remodeling of global DNA methylation was demonstrated in Arabidopsis during low phosphate availability. The presentstudy reports that AtMBD4 gene of Arabidopsis negatively regulates phosphate starvation. The T-DNA insertion mutation atthe AtMBD4 locus exhibited altered root architecture as compared to wild-type plants. Using microarray hybridization andanalysis, an increased transcript accumulation of 242 genes was observed in the mutant. Many of these genes were relatedto phosphate transporters and transcription factors, involved in phosphate starvation response. Comparison of data ofatmbd4 mutant with publicly available microarray data of phosphate starvation response indicated the role of AtMBD4protein in phosphate starvation response. Further, promoter analysis of up-regulated genes suggested that cis-regulatoryelements like MBS, W-box, and B1BS are more prominent in the promoters of up-regulated genes. Upon performing amethylation-specific PCR, a decreased DNA methylation in the promoter regions of up-regulated genes was observed. Theaccumulation of anthocyanin and inorganic phosphate in the atmbd4 mutant was found to be higher than the wild-typeplant. Altered root morphology, up-regulation of phosphate starvation-induced genes in atmbd4 mutant suggests thatAtMBD4 negatively regulates the phosphate starvation response.

Research on The Proteome Response of Acidithiobacillus ferrooxidans to Phosphate Starvation by SELDI-Protein Chip Technologies / 生物化学与生物物理进展

A cidithiobacillus ferrooxidans is a chemolithotrophic microorganism capable of using ferrous ions and sulphides as energy sources. This microorganism has an important role in the bioleaching of minerals. During this process, the bacteria are normally subjected to several stressing conditions, such as temperature changes, lack of nutrients or pH changes, which may affect the efficiency of the bacterial action. SELDI is a recent technology that allows for high-throughput proteomics studies. The Protein Chip SELDI technology was used to generate comparative protein profiles of A c idithiobacillus ferrooxidans grown under phosphate starvation or normal condition additionally adding Fe2+ as energy resource. There were 13 significantly differential expressed protein's peaks found by using SELDI Protein Chip technologies, which made a solid foundation for further isolation these low molecular proteins by adopting technologies such as HPLC etc.