P. Lopez-garcia et P. Forterre, DNA topology and the thermal stress response, a tale from mesophiles and hyperthermophiles, BIOESSAYS, 22(8), 2000, pp. 738-746
During heat shock and cold shock, plasmid DNA supercoiling changes transien
tly both in mesophilic bacteria and in hyperthermophilic archaea, despite a
different overall topology (negative supercoiling Versus relaxation to pos
itive supercoiling). Transient changes in DNA supercoiling might be essenti
al to generate the stress response, but they could also be a consequence of
the physical effects of temperature on cellular components. Indeed, both a
ppear intertwined. Comparison of the mechanisms acting in the two biologica
l systems suggests that the dependence on temperature of the activity of di
fferent DNA topoisomerases, as well as of protein binding, are key factors
for the control of DNA topology during stress, which may in turn be relevan
t for the expression of stress-induced genes. (C) 2000 John Wiley & Sons, I
nc.