J. Biol. Chem., Vol. 261, Issue 26, 11945-11948, 09, 1986
Turnover of cyclic 2,3-diphosphoglycerate in Methanobacterium thermoautotrophicum. Phosphate flux in P1- and H2-limited chemostat cultures
RD Krueger, JW Campbell and DE Fahrney
The archaebacterium Methanobacterium thermoautotrophicum was grown at 65
degrees C in H2- and Pi-limited chemostat cultures at dilution rates
corresponding to 3- and 4-h doubling times, respectively. Under these
conditions the steady state concentration of cyclic 2,3- diphosphoglycerate
was 44 mM in the H2-limited cells and 13 mM in the cells grown under Pi
limitation. Flux of Pi into the cyclic pyrophosphate pool was estimated by
two 32P-labeling procedures: approach to isotopic equilibrium and
replacement of prelabeled cyclic diphosphoglycerate with unlabeled
compound. The results unequivocally demonstrate turnover of the phosphoryl
groups; either both phosphoryl groups of the cyclic pyrophosphate leave
together or the second leaves at a faster rate. The half-life of the
rate-determining step for loss of the phosphoryl groups was approximately
equal to the culture doubling time. The Pi flowing into the cyclic
diphosphoglycerate pool accounted for 19% of the total Pi flux into
Pi-limited cells and 43% of the total for H2-limited cells. The high
phosphate flux through the large cyclic diphosphoglycerate pool suggests
that this molecule plays an important role in the phosphorus metabolism of
this methanogen.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?