This
antibiotic originating from the
Gram+ actinomycete
Streptomyces venezulenza has about the same type of activity as
cycloheximide, but than with an effect on
prokaryotes instead of
eukaryotes: it inhibits the peptidyl
transferase activity of the 50S
ribosomal subunit (the 50S is the larger half of the ribosome,
both parts together
translate mRNA+
tRNA into the basic
chain of
aminoacids that make up a
protein).
However,
archaebacteria couldn't care less about chloramphenicol because
of their unique and ancient type of ribosome, wich is different from the
"standard" bacteria (
eubacteria, the ones mentioned above under
prokaryotes).
The genes coding for
resistance for chloramphenicol are located on a
resistance plasmid (R-plasmid), happily togerther with the genes coding
for resistance for
antibiotics like
streptomycin,
tetracycline and a
few more. This makes it easier and more efficient for the bacteria to pass
on their information about how to combat all those antibitics in the
environment.