Erschienen:
Proceedings of the National Academy of Sciences, 1986
Erschienen in:
Proceedings of the National Academy of Sciences, 83 (1986) 6, Seite 1757-1761
Sprache:
Englisch
DOI:
10.1073/pnas.83.6.1757
ISSN:
0027-8424;
1091-6490
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>
A 47-base-pair (bp) conserved sequence in the 5′-flanking regions of three transcriptional units coding for nodulation functions (
<jats:italic>nod</jats:italic>
ABC,
<jats:italic>nod</jats:italic>
EFG, and
<jats:italic>nod</jats:italic>
H) has been identified in
<jats:italic>Rhizobium meliloti</jats:italic>
strain 41. The conserved region contains subsequences of 7 bp, 5 bp, and 25 bp. The conserved 25-bp sequence was synthesized and used as a hybridization probe; three additional copies of the sequence were identified in
<jats:italic>R. meliloti</jats:italic>
41; all three were localized in the 135-kb
<jats:italic>nod/nif</jats:italic>
region of the symbiotic megaplasmid. Nucleotide sequence analysis of the six regions revealed that all contained the 47-bp conserved sequence but, with one exception, adjacent DNA regions did not have long conserved DNA stretches. The position of the 47-bp region was about 200-240 bp upstream of the translational start codons of the three
<jats:italic>nod</jats:italic>
genes. This conserved sequence is present in several other
<jats:italic>Rhizobium</jats:italic>
species and located adjacent to
<jats:italic>nod</jats:italic>
genes. We have demonstrated the involvement of this sequence in the expression of nodulation functions, which suggests that these extended promoter regions may have a role in the coordinated regulation of nodulation genes.
</jats:p>