Js. Kroll et al., NATURAL GENETIC EXCHANGE BETWEEN HAEMOPHILUS AND NEISSERIA - INTERGENERIC TRANSFER OF CHROMOSOMAL GENES BETWEEN MAJOR HUMAN PATHOGENS, Proceedings of the National Academy of Sciences of the United Statesof America, 95(21), 1998, pp. 12381-12385
Members of the bacterial families Haemophilus and Neisseria, important
human pathogens that commonly colonize the nasopharynx, are naturally
competent for DNA uptake from their environment. In each genus this p
rocess is discriminant in favor of its own and against foreign DNA thr
ough sequence specificity of DNA receptors, The Haemophilus DNA uptake
apparatus binds a 29-bp oligonucleotide domain containing a highly co
nserved 9-bp core sequence, whereas the neisserial apparatus binds a 1
0-bp motif, Each motif (''uptake sequence'', US) is highly over-repres
ented in the chromosome of the corresponding genus, particularly conce
ntrated with core sequences in inverted pairs forming gene terminators
. Two Haemophilus core USs were unexpectedly found forming the termina
tor of sodC in Neisseria meningitidis (meningococcus), and sequence an
alysis strongly suggests that this virulence gene, located next to IS1
106, arose through horizontal transfer from Haemophilus. By using USs
as search strings in a computer-based analysis of genome sequence, it
was established that while USs of the ''wrong'' genus do not occur com
monly in Neisseria or Haemophilus, where they do they are highly likel
y to flag domains of chromosomal DNA that have been transferred from H
aemophilus. Three independent domains of Haemophilus-like DNA were fou
nd in the meningococcal chromosome, associated respectively with the v
irulence gene sodC, the bio gene cluster, and an unidentified orf. Thi
s report identifies inter-generically transferred DNA and its source i
n bacteria, and further identifies transformation with heterologous ch
romosomal DNA as a way of establishing potentially important chromosom
al mosaicism in these pathogenic bacteria.