TY - JOUR
T1 - Studies on the cytoplasmic protein tyrosine kinase activity of the Antarctic psychrotrophic bacterium Pseudomonas syringae
AU - Jagtap, Pratik
AU - Ray, M. K.
PY - 1999/4/15
Y1 - 1999/4/15
N2 - The Antarctic psychrotrophic bacterium Pseudomonas syringae contains a 66-kDa cytoplasmic protein which was found to be phosphorylated on a tyrosine residue [Ray, M.K. et al. (1994) FEMS Microbiol. Lett. 122, pp. 49-54]. To investigate the nature of the cytoplasmic protein tyrosine kinase and its role in the bacterial physiology, we carried out some biochemical studies of the enzyme in vitro in the presence of exogenous peptide substrates and expression studies in vivo at low and high temperature during various phases of growth. The results suggest that the protein tyrosine kinase associated with the cytoplasmic fraction of the bacterium has certain similarities and dissimilarities with the known eukaryotic tyrosine kinases. The protein tyrosine kinase could phosphorylate exogenous substrate corresponding to the N-terminal peptide of p34(cdc2) kinase but could not do so on poly(Glu:Tyr). The enzyme could not be inhibited by genistein, staurosporine and dimethyl aminopurine, but could be inhibited by piceatannol which is a known competitive inhibitor of the peptide binding site of mammalian protein tyrosine kinases. The enzyme activity in the cytoplasm is uniquely inhibited by sodium orthovanadate (IC50=20 μM) which is a known protein tyrosine phosphatase inhibitor. The expression studies show that the enzyme is produced more at a higher temperature (22°C) of growth than at lower temperature (4°C) and during the stationary phase of growth of P. syringae. Copyright (C) 1999 Federation of European Microbiological Societies.
AB - The Antarctic psychrotrophic bacterium Pseudomonas syringae contains a 66-kDa cytoplasmic protein which was found to be phosphorylated on a tyrosine residue [Ray, M.K. et al. (1994) FEMS Microbiol. Lett. 122, pp. 49-54]. To investigate the nature of the cytoplasmic protein tyrosine kinase and its role in the bacterial physiology, we carried out some biochemical studies of the enzyme in vitro in the presence of exogenous peptide substrates and expression studies in vivo at low and high temperature during various phases of growth. The results suggest that the protein tyrosine kinase associated with the cytoplasmic fraction of the bacterium has certain similarities and dissimilarities with the known eukaryotic tyrosine kinases. The protein tyrosine kinase could phosphorylate exogenous substrate corresponding to the N-terminal peptide of p34(cdc2) kinase but could not do so on poly(Glu:Tyr). The enzyme could not be inhibited by genistein, staurosporine and dimethyl aminopurine, but could be inhibited by piceatannol which is a known competitive inhibitor of the peptide binding site of mammalian protein tyrosine kinases. The enzyme activity in the cytoplasm is uniquely inhibited by sodium orthovanadate (IC50=20 μM) which is a known protein tyrosine phosphatase inhibitor. The expression studies show that the enzyme is produced more at a higher temperature (22°C) of growth than at lower temperature (4°C) and during the stationary phase of growth of P. syringae. Copyright (C) 1999 Federation of European Microbiological Societies.
KW - Antarctic psychrotroph
KW - Protein tyrosine kinase activity
KW - Pseudomonas syringae
UR - http://www.scopus.com/inward/record.url?scp=0033043956&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033043956&partnerID=8YFLogxK
U2 - 10.1016/S0378-1097(99)00105-6
DO - 10.1016/S0378-1097(99)00105-6
M3 - Article
C2 - 10227168
AN - SCOPUS:0033043956
SN - 0378-1097
VL - 173
SP - 379
EP - 388
JO - FEMS Microbiology Letters
JF - FEMS Microbiology Letters
IS - 2
ER -