Proteomic analysis of alterations in the secretome of Arabidopsis thaliana suspension cells subjected to nutritional phosphate deficiency

• Published in: Proteomics (Weinheim) Vol. 8; no. 20; pp. 4317 - 4326
• Main Authors: Tran, Hue T, Plaxton, William C
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley-VCH Verlag 01.10.2008; WILEY‐VCH Verlag; Wiley-VCH
• Subjects: Acid Phosphatase - metabolism; Analytical, structural and metabolic biochemistry; Arabidopsis; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - secretion; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Glycoproteins - metabolism; Miscellaneous; Peptide mass fingerprinting; Phosphate starvation; Phosphates - deficiency; Protein Sorting Signals - physiology; Proteins; Proteome - metabolism; Secreted protein; Peptides; Secretion; Arabidopsis; Nutrition disorder; Protein; Arabidopsis thaliana; Peptide mass fingerprinting; Secreted protein; Cruciferae; Dicotyledones; Fingerprint method; Phosphate starvation; Angiospermae; Proteomics; Spermatophyta; Nutritional deficiency
• ISSN: 1615-9853; 1615-9861
• DOI: 10.1002/pmic.200800292

A proteomic approach was applied to compare the secretome (culture filtrate proteome) of phosphate-sufficient (+Pi) and Pi-deficient (-Pi) Arabidopsis thaliana suspension cell cultures. Secretomes harvested from the +Pi and -Pi cells yielded dissimilar 2-DE maps. PMF via MALDI-TOF MS resulted in the identification of 50 protein spots representing 37 discrete proteins having unique gene identities. A total of 24 Pi-starvation responsive proteins were identified, with 18 of these being up-regulated and six down-regulated. Secreted proteins up-regulated by the -Pi cells included a ribonuclease involved in Pi scavenging from extracellular nucleic acids, as well as enzymes of cell wall modification, proteolysis, pathogen responses, and ROS metabolism. Enzyme activity assays and immunoblotting demonstrated that a pair of purple acid phosphatase isoforms having subunit Mrs of 65 and 55 kDa was also secreted by the -Pi cells. Semiquantitative RT-PCR was used to assess the relationship between mRNA levels and relative amounts of selected secretome proteins. The results indicate that transcriptional control is but one of many factors contributing to Arabidopsis Pi starvation responses, and highlight the importance of parallel biochemical/proteomic studies of -Pi plants.