Tyrosine phosphatase signalling in a lower plant: cell-cycle and oxidative stress-regulated expression of the Chlamydomonas eugametos VH-PTP13 gene.
The first evidence for tyrosine phosphatase signalling pathways in plants is presented by characterizing a putative protein tyrosine phosphatase gene from the unicellular green alga Chlamydomonas eugametos. This cDNA, referred to as VH-PTP13, contains an open reading frame specifying a protein with a molecular weight of 30.3 kDa, that has significant homology with a distinct group of dual-specificity phosphatases. The highest homology is found with CL-100, a human stress-response gene that regulates MAPkinase activity. The purified VH-PTP13 protein expressed in E. coli had phosphatase activity and inactivated MAPkinases from alfalfa and tobacco. Nondividing C. eugametos gametes did not express the VH-PTP13 gene whereas synchronously dividing vegetative cells only expressed VH-PTP13 in the early G1-phase of the cycle, implying a function there. When vegetative cells were subjected to oxidative stress, expression of the VH-PTP13 gene was strongly induced, analogous to the human CL-100 gene. Its potential role in plant signalling pathways is discussed.
Haring
M A
MA
Biocentrum Amsterdam, University of Amsterdam, The Netherlands.
Siderius
M
M
Jonak
C
C
Hirt
H
H
Walton
K M
KM
Musgrave
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D002696:Chlamydomonas / Q000201:enzymology / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D054640:Dual Specificity Phosphatase 3; D004926:Escherichia coli; D005786:Gene Expression Regulation; D000455:Medicago sativa / Q000201:enzymology / Q000235:genetics; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010802:Phylogeny; D047428:Protein Kinase Inhibitors; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism*
D018076:DNA, Complementary; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins; D014443:Tyrosine; C517025:DUSP3 protein, human; D054640:Dual Specificity Phosphatase 3; D017027:Protein Tyrosine Phosphatases