Structure, evolution and expression of a second subfamily of protein phosphatase 2A catalytic subunit genes in the rice plant (Oryza sativa L.).
Protein phosphatase 2A (PP2A) is one of the major serine/threonine protein phosphatases in the cell and plays a variety of regulatory roles in metabolism and signal transduction. Previously, we described the structure and expression of two genes encoding PP2A catalytic subunits (PP2Ac)--OsPP2A-1 and OsPP2A-3--in the rice plant (Yu et al. 2003). Here, we report the isolation and characterisation of a second structurally distinguishable PP2Ac subfamily comprised of three additional isogenes, OsPP2A-2, OsPP2A-4 (each containing ten introns) and OsPP2A-5 (which contains nine introns). Northern blot analysis demonstrated that the three isogenes are ubiquitously expressed in all rice tissues during plant development, and differentially expressed in response to high salinity and the combined stresses of drought and heat. Phylogenetic analyses indicated that the two PP2Ac subfamilies are descended from two ancient lineages, which derived from gene duplications that occurred after the monocotyledon-dicotyledon split. In the second subfamily, it is proposed that two duplication events were involved; in which, the initial duplication of a ten-intron primordial gene yielded OsPP2A-2 and the progenitor of OsPP2A-4 and OsPP2A-5. The OsPP2A-4/OsPP2A-5 progenitor, in turn, underwent a second duplication event, resulting in the present day OsPP2A-4 and OsPP2A-5. It is proposed that loss of the 5'-most intron from OsPP2A-5 occurred after these two duplication events.
Yu
Richard Man Kit
RM
Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong.
Wong
Minnie Man Lai
MM
Jack
Ralph Wilson
RW
Kong
Richard Yuen Chong
RY
D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D020440:Gene Duplication; D015870:Gene Expression; D017343:Genes, Plant; D018745:Genome, Plant; D008969:Molecular Sequence Data; D005810:Multigene Family; D012275:Oryza / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000235:genetics*; D010802:Phylogeny; D054648:Protein Phosphatase 2; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D018076:DNA, Complementary; D018744:DNA, Plant; D021122:Protein Subunits; D012333:RNA, Messenger; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2