E. coli competence

mol13 at msus1.msus.edu mol13 at msus1.msus.edu
Thu Sep 22 15:17:57 EST 1994


I would like to comment on some remarks made concerning E. coli competence and
the possibility
that bacteria may communicate with one another as well as the suggestion that
there is a connection
therefore to the eukaryotic realm.

My work began as a study of how stress-related neuroendocrine hormones can
affect disease
progression.  To make a long story short (and to save bandwidth), the
conventional explanations that
stress affects immune responses and that affects our resistance to infectious
disease did not seem as
strong as is believed by the vast majority of researchers.  Instead, I proposed
(and have published
four papers) that bacteria do in fact respond to neuroendocrine signals. 
Specifically, my group has
shown that the growth of gram-negative bacteria can be increased in a
non-nutritional manner over
100,000-fold in response to certain neuroendocrine signals.  A simple
difference of one carbon atom
between one hormone and the next or its metabolite is enough to obviate any
effect.  Further, the
elaboration of virulence factors can also be influenced.

I think it is important to remember that the majority of neuroendocrine
hormones we associate with
mammalian systems are found widely dispersed throughout nature (bananas contain
such a high
catecholamine content, albeit in the peel, that during the late 1950's and
early 1960's it was debated if
heart attack patients should eat bananas for fear of the effect of added
catecholamines on the heart). 
Further, there is a wide literature on the presence of various neuroendocrine
hormones and their
respective receptors ranging from growth hormone to insulin being found in
numerous
microorganisms.  

The evolution of microorganisms preceded that of vertebrates such as man.  Is
it such a far stretch to
suggest that bacteria can communicate with one another through various
neuroendocrine hormones? 
And if this is so, the presence of hormones in microorganisms therefore
suggests that recognition of
mammalian hormones by microorganisms might serve as a type of environmental cue
by which
microorganisms may sense their surroundings and initiate pathogenic processes.  

I agree with others who have raised the subject of cell-cell communication that
experiments need to be
performed between various groups.  An interdisciplinary group approach, which
could be
accomplished through the net, could be very powerful.

Mark Lyte
Department of Biological Sciences
Mankato State University
Mankato, Minnesota
e-mail: MOL13 at msus1.msus.edu




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