The peptide methionine sulfoxide reductase A (PMSRA) gene family in Arabidopsis consists of five members. Three are localized in chromosome five (encoding cytosolic proteins), one in chromosome four (encoding a plastid proteins) and one in chromosome two (encoding a protein targeted for secretion). Analysis of the sequence showed that four of the proteins (PMSRA1 to PMSRA4) have a conserved catalytic domain GCFWG and a domain unique for plants PIRCYG (PMSRA5 does not have any of them). To establish detailed expression data of this gene family, comprehensive in silico and RT-PCR analyses for the five PMSRAs were conducted. This included analysis of organ-specific and developmental expression and expression in response to oxidative stress induced by high light, paraquat, cercosporin and ozone. All genes are expressed in the different plant organs. PMSRA4 is predominant in all tissues except roots. PMSRA1 to PMSRA3 have higher expression in roots and stems. PMSR1 is more expressed in flower buds and PMSRA5 in stems. Promoter analysis showed the presence of cis responsive elements to different stress conditions such as metals, extreme temperatures, pathogens, water stress, high light salinity. RT-PCR analysis showed that PMSRA4 is up-regulated by oxidative stress conditions, especially by high light that induced an eight-fold increase in mRNA. The other genes were not as responsive. To further characterize the PMSRA family, recombinant plastid PMSRA4 and one cytosolic PMSRA (PMSRA3) were overexpressed in Escherichia coli and purified. Kinetic parameters (K M, kcat, kcat/KM) were measured for both proteins using FMOC/MetSO as a substrate.
All Science Journal Classification (ASJC) codes
- Agronomy and Crop Science
- Plant Science