tailieunhanh - báo cáo khoa học: " Non-redundant functions of two proline dehydrogenase isoforms in Arabidopsis"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Non-redundant functions of two proline dehydrogenase isoforms in Arabidopsis | Funck et al. BMC Plant Biology 2010 10 70 http 1471-2229 10 70 BMC Plant Biology RESEARCH ARTICLE _ Open Access Non-redundant functions of two proline dehydrogenase isoforms in Arabidopsis Dietmar Funck Sonja Eckard and Gudrun Muller Abstract Background Proline Pro accumulation is a widespread response of prokaryotic and eukaryotic cells subjected to osmotic stress or dehydration. When the cells are released from stress Pro is degraded to glutamate by Prodehydrogenase ProDH and Pyrroline-5-carboxylate dehydrogenase P5CDH which are both mitochondrial enzymes in eukaryotes. While P5CDH is a single copy gene in Arabidopsis two ProDH genes have been identified in the genome. Until now only ProDHl At3g30775 had been functionally characterised. Results We demonstrate vasculature specific expression of the Arabidopsis ProDH2 gene At5g38710 as well as enzymatic activity and mitochondrial localisation of the encoded protein. Expression levels of ProDH2 are generally low but increased in senescent leaves and in the abscission zone of floral organs. While sucrose represses ProDH2 expression Pro and NaCl were identified as inducers. Endogenous ProDH2 expression was not able to overcome Pro sensitivity of ProDHl mutants but overexpression of a GFP-tagged form of ProDH2 enabled the utilisation of Pro as single nitrogen source for growth. Amongst two intronic insertion mutants one was identified as a null allele whereas the other still produced native ProDH2 transcripts. Conclusions Arabidopsis possesses two functional ProDHs which have non-redundant although partially overlapping physiological functions. The two ProDH isoforms differ with respect to spatial developmental and environmental regulation of expression. While ProDHl appears to be the dominant isoform under most conditions and in most tissues ProDH2 was specifically upregulated during salt stress when ProDHl was repressed. The characterisation of ProDH2 as a functional gene requires a careful .